Title of Invention	A METHOD FOR SETTING UP A COMMUNICATION LINK BETWEEN TWO CLIENTS OF A PLURALITY OF CLIENTS IN A DIRECTLY COMMUNICATING COMMUNICATION NETWORK
Abstract	The invention relates to a method for setting up a communication link between two clients of a plurality of clients in a directly-communicating communication network, in which signaling information comprising client address information is interchanged between clients who wish to be involved in the communication link, in order to set up the communication link, the communication link is set up directly between the clients who wish to be involved in the communication link, on the basis of the client address information, following method steps which carried out successively a) a first communication link exists between a calling client and a second client, the client address information of a destination client being transmitted by the second client to the calling client, b) the first communication link is cleared c) the calling client uses this client address information to set up the communication link between the calling client and the destination client, and d) the communication link set up in step c) between the calling client and the destination client is taken down and the first communication link is set up again.

Title of Invention

A METHOD FOR SETTING UP A COMMUNICATION LINK BETWEEN TWO CLIENTS OF A PLURALITY OF CLIENTS IN A DIRECTLY COMMUNICATING COMMUNICATION NETWORK

Abstract

The invention relates to a method for setting up a communication link between two clients of a plurality of clients in a directly-communicating communication network, in which signaling information comprising client address information is interchanged between clients who wish to be involved in the communication link, in order to set up the communication link, the communication link is set up directly between the clients who wish to be involved in the communication link, on the basis of the client address information, following method steps which carried out successively a) a first communication link exists between a calling client and a second client, the client address information of a destination client being transmitted by the second client to the calling client, b) the first communication link is cleared c) the calling client uses this client address information to set up the communication link between the calling client and the destination client, and d) the communication link set up in step c) between the calling client and the destination client is taken down and the first communication link is set up again.

Full Text	FIELD OF THE INVENTION The invention relates to a method for setting up a communication link between two clients of a plurality of clients in a directly-communicating communication network as claimed in the precharacterizing clause of patent claim 1. BACKGROUND OF THE INVENTION Communication networks whose components communicate with one another by packet switching are being used increasingly instead of line-switching communication networks. Networks such as these are frequently also referred to as Voice-Over-IP (VoIP) networks, when the Internet Protocol (IP) is used to interchange acoustic information (speech data) in the form of data. In this case, the networks may either be used exclusively for transmission of speech data or else can transmit both speech data and other information (for example data, video) as well in a mixed form. In line-switching communication networks, terminals (for example telephones, fax machines) are always connected to a communication node (for example to a telephone system). The entire information flow to and from the terminals in this case takes place with the involvement of the respective communication node, with control information, for example for setting up links, being interchanged between the terminal and the communication node, while the payload information (the analog speech signal of the modulated fax signal) is admittedly interchanged between the terminals that are involved in the communication link but is passed on (transmitted) by at least one communication node that is involved in the communication link. In speech data networks, the terminals are frequently referred to as "clients", because the terminals in these communication networks are operated in a similar manner to a computer in a data network and not only as a telephone or fax machine, but may also, for example be in the form of a multimedia PC. A multimedia PC is a computer which has suitable hardware for inputting information (for example a microphone, camera, keyboard, scanner etc.) and for outputting information (for example, a screen/display, loudspeakers, LEDs etc.). Clients may also be in the form of a miniature PC (so-called PDA - Personal Digital Assistant) or an extended mobile telephone (smart phone). The appliances mentioned are often equipped with a cordless data link and, in the case of mobile telephones are then also referred to as "WLAN cellphones" (WLAN = Wireless Local Area Network). The clients in speech data networks generally interchange the payload information directly with one another. For this purpose, once a communication link has been set up, two clients communicating with one another each interchange the data packets with the payload information with the knowledge of the network address of their communication partner, and on the basis of these network addresses. In order to set up a link, by contrast, central network nodes (communication nodes) are also used in the known speech data networks. Network nodes such as these are known to the speech data networks which use H.323 protocol (ITU-T-H.323) as "gatekeeper" and to the speech data networks which use the SIP protocol (IETF-SIP; SIP = Session Initiation Protocol), as SIP proxy servers. Widespread data networks, in particular, the Internet, are increasingly using communication structures which are referred to as "peer-to-peer" networks or else "end-to-end" networks. One primary field of application for communication structures such as these is to interchange files, so-called "file sharing". In this case, a subscriber (client) to a communication structure such as this checks a number of other clients (typically computers) when looking for a specific resource (which may be a music file or a computer program) , and starts to use this resource once it has been found, which generally involves the transmission ("download") of one or more files. In this case, either appropriate communication partners (clients) are found using a database, or else the clients can be found by appropriate communication methods without any central instance. Some of the known "peer-to-peer" networks are used for the purpose of direct communication. The "media data" that is interchanged in this case, that is to say the payload data, is not restricted to speech (speech data) or modulated information (for example fax transmissions), but also includes moving image information (video transmission, video conferences, "multimedia messaging") and other forms of electronic communication. In communication networks such as these, which are also referred to as "directly-communicating communication networks", this means on the one hand that communication links can be set up in the form of conventional "telephone calls", while on the other hand it is also possible to transmit extended contents ("multimedia"). Avoiding the use of central network nodes (communication nodes) in this case results in the advantage of increased resistance to failures, although it is associated with the disadvantage that the (switching) functionality of the network nodes, as is known from line-switching telephony must be provided by the clients involved in the communication link, themselves. The document US 2003/0095546 Al Sakano et al. "IP Telephone terminal searching for destination with a telephone number to set up a call connection over an IP network" has already disclosed a directly communicating communication network in which clients set up direct communication links with one another using addresses (IP addresses). In this case it is proposed to send a search message with a call number to adjacent clients, whereby, in cases in which a client who receives the search message is allocated this call number, this client makes his IP address available to the first, searching client in order to initiate a communication link on the basis of the Internet protocol. In the case of the known directly-communicating communication networks, it has been found to be particularly disadvantageous when a client must have the address information (for example the network address) of a second client in order to set up a communication link to that second client. This is a problem because, in general, there is no network node (for example communication server) directly associated with the client, with which it is possible to check an address such as this. Even if the address information for the desired communication partner is known, it is possible in directly-communicating communication networks that it is not possible to reach this desired communication partner (for example if it is "busy" or if the client has failed) so that, for example it is desirable to set up a link to an alternative call destination ("alternative destination"). Since directly-communicating communication networks do not use central network nodes for storage of address information such as this, the problem of addressing still exists when setting up a connection to an alternative call destination such as this. One object of the invention is to propose a method by means of which the address information which is required for communication links in directly-communicating communication networks can be determined. The object is achieved by the features of the invention, in that the following method steps are carried out successively: first of all (step a) client address information which is required to set up a communication link between the clients in pairs is stored for at least one destination client in a first client. Then (step b), the stored client address information for the destination client is transmitted from the first client to a calling client, and then (step c) the calling client uses this client address information to set up the communication link between the calling client and the destination client. When the abovementioned method steps are carried out, this results in a calling client in the directly-communicating communication network having transmitted to it the address of the destination client that is required to set up a communication link, with the link being set up without any access to a central communication node or to a central address database. The fact that call forwarding has been carried out can remain concealed for the calling client if the destination client forms the call forward destination for the first client in step a) , and when a call arrives from the calling client, the first client sends signaling information for call signaling of a further call to the destination client in step b), in which case on acceptance of the further call at the destination client, the latter transmits a call acceptance signaling message to the first client, on the basis of which the first client transmits the client address information for the destination client to the calling client. In this case the call forwarding is carried out not only when the first client is busy but also in the case of a call which is not accepted by the first client, in that the signaling information for call signaling of the further call is transmitted to the destination client if the call is not answered at the first client within a waiting time. This waiting time can advantageously be set or changed by a user at the first client, by means of an input. The feature of "call forwarding" can advantageously be made use of for this purpose in the event of an unsuccessful call to a free subscriber (client) in that the details about waiting time are stored in the first client in step a) , and a call is signaled to the first client in step b), on the basis of the received signaling information, and the stored client address information is transmitted to the calling client only if the call to the first client is not answered within the waiting time. The method allows features to be provided in a directly-communicating communication network without the inclusion of a central switching instance, in which case, as a further advantage, the lack of a central communication node or of a central subscriber directory results in a high degree of operational reliability and availability in the communication network because, in the event of a failure of one communication component (dient) only a relatively small portion of the communication network is affected. Furthermore, communication networks which use the method according to the invention can be extended more easily and can be scaled better. Call forwarding can be set up and carried out in a simple manner and in that in order to forward a call, the destination client forms the call forward destination for the first client in step a), and the calling client sends signaling information for call signaling to the first client between steps a) and b), in order to set up a communication link. In the case of call-forwarding, a user at the first claim can enter various call- forwarding destinations, with a suitable one of the call forwarding destinations being selected depending on the nature (service) of the call arriving at tiie first client or of the communication link that is intended with the call. This is achieved in that the client address information for a plurality of destination clients is stored in the first client in step a), and is in each case associated with one or more different services, and when call arrives at the first client, the signaling information in step b) defines the service which is intended to be supported by the communication link to be set up, with the client address information for that destination client which is associated with this service being selected and transmitted on the basis of this definition. In this case, the services are advantageously selected from a group which comprises at least speech services, video services and data services. The method according to the invention allows a call to be signaled to a plurality of clients at the same time and to be answered at any desired one of these clients in that the destination client is provided as the follow-me destination in step a), the calling client sends signaling information for call signaling to the first client between steps a) and b) in order to set up a communication link, and the call signaling takes place both at the first client and at the destination client in step c) in that the calling client sends further signaling information for call signaling to the destination client with the communication link being set up between the calling client and the destination client when the call is accepted at the destination client. In the case of follow-me, it is possible to avoid a situation in which the calling client sends signaling information to a plurality of clients, in that, in this case as well, the destination client is provided as the follow-me destination in step a) , between steps a) and b), the calling client sends signaling information for call signaling to the first client in order to set up a communication link, and the call signaling takes place both at first client and at the destination client, in that the first client sends further signaling information for call signaling of a further call to the destination client, with the destination client sending a call acceptance message to the first client after acceptance of this call, and the first client also transmitting the call reception message with the client address information of the destination client to the calling client in step b). The method allows the feature of "callback" to be provided in a simple manner in a directly-communicating communication network, in that in order to prepare for a callback, in situations in which an incoming call from the destination client to the first client is not accepted in step a) , the destination client stores the client address information together with the callback information in the first client, and in order to carry out the callback in step b) the first client, as the calling client, requests the destination client to carry out the callback. In this case, the callback when the client is busy is requested in that step a) is carried out when the first client is in the busy state and, the callback is made when the busy state of the first client no longer exists. In contrast to this, a callback can also be requested in the case of a client which is not busy and to which a call has been signaled unsuc- cessfully in that step a) is carried out when the incoming call has not been accepted at the first client within a waiting time, and the callback is completed when an event which reflects the presence of a user is detected at the first client. An event such as this advantageously does not need to be an explicit reaction by a user to a callback request, so that the callback is initialized with as short a time delay as possible, for example when a person returns to his desk. Various non-central message stores (speech boxes, video stores, e-mail system, etc.) can be used in directly-communicating communication networks in that in order to record and to call a message which is intended for the first client, before step a), a second client sets up a communication link to the destination client with the message being stored in the destination client, after step a) the presence of the stored message is signaled to the first client, in step b) in turn, the calling client is formed by the first client, and in step c) the stored message is called up at the destination client using the communication link. In this case, various services can be used in the communication network, in which case a plurality of recording clients for storage of messages are available in the communication network, and, before step a) the second client selects a suitable one of the recording clients as the destination client. In this case, in each case at least one type of recordable message is advantageously associated with the recording client in which case, in step a) in each case one recording client is selected which is appropriate for the type of message to be recorded. In the event of a brief interruption in an existing communication link, for example for questions, it is advantageous for a subscriber (client) who is waiting during the interruption to be supplied with information (for example waiting music, product information, etc.). This can be achieved in that a first communication link exists between the first client and the second client in step a) , with the client address information for the destination client being transmitted by the second client to the first client, the first client forms the calling client in step b), and the first communication link is cleared after step b), and after step c), the communication link which was set up in step c) between the calling client and the destination client is cleared, and the first communication link is set up again. In this case, the destination client is advantageously used as the information source for waiting times. Before the interruption of the first communication link, a user of the second client can decide which contents and which type of media (speech, images, text information, etc.) should be output to the first client during the waiting time. This is achieved in that a plurality of clients can be used as the destination client in the communication network, with one of the usable clients being selected as the destination client by the second client in step a) . In this case, the destination client can advantageously be in the form of an instance on the same hardware, which forms the basis for the first or for the second client. In a directly-communicating communication network, announcements can be emitted to clients in a simple manner, in which case a client who is receiving the announcement can be activated automatically without a user having to do anything in that in step c) the calling client, when setting up the communication link, transmits call signaling information along with a control command to the destination client so that the call is automatically accepted by the destination client. Exemplary embodiments of the method according to the invention will be explained in the following text with reference to the drawings, in which: Figures 1a, 1b show the interchange of signaling information between clients in a directly-communicating communication network, for the purpose of call forwarding when free, Figures 1c, 1d show the interchange of signaling information for call forwarding when busy, Figure 2a shows an arrangement of clients in a directly- communicating communication network for provision of follow-me in a first variant, Figure 2b shows the interchange of signaling information for the implementation of follow-me in a second variant, Figure 3a shows the initiation of a callback for a busy client, Figure 3b shows the interchange of signaling information for initiation and for carrying out a callback for a busy client, Figure 3c shows the signaling of a call for a free (not busy) client, Figure 3d shows the signaling information for the initiation and for carrying out a callback for a free client, Figure 4a shows the storage of a message for a client and the signaling of a stored message for this client, Figure 4b shows the calling up of the stored message by the notified client, and Figure 5 shows the supply of a client with waiting information while a communication link is on hold. Figure la shows a schematic illustration of clients A, B, C who are arranged in a directly-communicating communication network (not illustrated) . The clients A, B, C in this and in the following exemplary embodiments are in the form of multimedia PCs which set up communication links with one another in a packet-switching communication network (IP network; IP = Internet Protocol) by interchanging signaling information (control messages) with one another. These control messages are represented as arrows in the figures with the direction of the arrow in each case indicating the direction of the information flow of the respective control message. In this case, a multiple data interchange can take place between the clients interchanging the control message in order to interchange said control message, for example in order to acknowledge reception of the control message in a so-called "handshake process". In the case of the communication links between the clients as illustrated schematically in the figures, there is in each case a logic relationship between two clients, with data packets with payload information being transmitted between the clients on the basis of previously interchanged client address information. The payload information may optionally be speech information (speech data) or other contents (for example, video information, text information), and mixed forms of the various types of information (these are also referred to as "services") are possible. The clients, control messages and communication links which are known from Figure la and from the following figures are also used repeatedly in other figures with the same reference symbols. These are then clients, control messages and communication links with essentially the same functions, and are therefore not described again in the description of the further figures. Instead of the multimedia PCs that were used as clients in the figures, it is also possible to use any other desired components intended for communication, for example telephony terminals (IP telephones, VoIP telephones; VoIP = Voice-over Internet Protocol), fax machines, etc. The significant factor for the clients described here is that they are designed for operation in directly-communicating communication networks, that is to say their function and interaction with other clients and devices in a communication network take place without the use of a central instance, for example a communication node or a central server. This principle is still applicable when the functionality of a client is not sufficient to carry out a specific task, and this client therefore appoints a proxy to carry out the functionality that it is missing. The implementation of the feature "call forwarding" with the aid of the method according to the invention will be described in the following text with reference to Figures 1a, 1b, 1c and 1d, with Figures la and lb showing call forwarding in the case of a call to a free subscribe and Figures 1c and 1d showing call forwarding in the case of a call to a busy subscriber. In Figure la, a user of the client B as the first client has determined with an input that all calls which reach his terminal (client B) will be forwarded to the client C as the destination client after a waiting time TO1 (TO = Time Out) of 20 seconds if the call is not accepted at the client B within this waiting time TOl. Let us assume that a communication link is intended to be set up to a client B from the client A as the calling client. For this purpose, the client A sends a call signaling message RSI to the client B, which initiates call signaling (the client B "rings") at the client B. At the same time the client B sends an acknowledgment message AL1 ("alerting") to client A as acknowledgment. The call is not accepted at the client B, so that the waiting time TOl times out. The client B now sends a call redirect message RD1 (RD = Redirect) to the client A, which instructs the client A now to signal the call which was signaled to the client B to the client C as the destination client. The call redirect message RD1 in this case comprises the client address information for the client C, which has been entered by the user during his definition of the client C as the call forwarding destination. The signaling of the call to the client B is now stopped, and the client A, as the calling client, sends further call signaling information RS2 to the client C, after whose reception the client C starts to signal the call, and in response to which the client C sends an acknowledgment message AL2 ("alerting") to the client A for acknowledgment. Once the call has been accepted at the client C, the client C sends a call acceptance signaling message CN1 ("connect"), to the client A in response to which the communication link Kl (payload data link) is established between the client A and the client C. As a further example of call forwarding when free, Figure lb once again shows the waiting time TO1 being carried out in the client B as the first client by a user, and the client address information for the client C being defined as the call forwarding destination (destination client) for calls to the client B which are not accepted. In this case as well, a call from the client A to the client B takes place with the aid of the call signaling message RS1, with this call once again being acknowledged by the acknowledgment message AL1, and with the waiting time TOl also passing in this case without the call having been accepted at the client B. In contrast to the process described with reference to Figure la, the client B now ceases to signal the call and now uses a further call signaling message RS3 to the client C which, in addition to the command to signal a call to the client C, also includes the additional information that this call is a forwarded call from the client A. The call is now signaled to the client C, and an acknowledgment message AL3 is sent to the client B. Whilst the client C has accepted the call, the client C sends a call acceptance message CN3 to the client B in response to which the client B sends a further call acceptance message CN4 to the client A as the calling client, including the information that the call being signaled on the basis of the call signaling message RS1 has been forwarded to the client C, where it has been accepted. This call acceptance message CN4 also includes the client address information for the destination client, client C, so that the communication link K1 is now set up between the client A and the client C. Figure 1c shows call forwarding when busy, in a first variant. At the client B as the first client, a user defines the client C as the destination client for call forwarding when busy. In this case, the client address information for the destination client C is also stored in the client B. The client A now sends call signaling messages RS1 to the client B which, however, is already busy with a further communication link, which is not illustrated here. On the basis of the stored information, the client B now sends a call redirect message RD2 (for call forwarding) to the client A, including the designation and the client address information for the client C as the destination client, and also including the information that the client B is busy and that this call will thus be forwarded to the client C. As the calling client, the client A now sends further call signaling information RS2 to the client C, by which means the call is signaled to the client C, and the acknowledgment message AL2 is sent to the client A. After acceptance of the call at the client C, the client C sends out call acceptance message CN1 to the client A, after whose reception the communication link K1 is set up between the client A and the client C. Figure 1d also shows the signaling messages which are interchanged between the clients A, B, C in order to carry out call forwarding when busy. In this variant as well, the name and the client address information for the client C as the destination client for call forwarding when busy are stored in the client B as the first client. Client A now once again sends call signaling messages RS1 to the client B, with the client B also being busy in this case and not itself signaling the call. The client B now sends further call signaling messages RS4 to the client C, from which call signaling message it is evident that the call is the call which originated from the client A. In this case, the client address information for the client A, which is transmitted with the call signaling message RS1 to the client B, is also passed to the client C. The call is now signaled to the client C with this fact being signaled by means of the acknowledgment message AL4 from the client C to the client B. After reception of the acknowledgment message AL4, the client B sends an acknowledgment message AL5 to the client A, from which it is evident that the call that was initiated by the call signaling message RS1 has been forwarded to the client C and is now being signaled to the client C. After acceptance of the call at the client C, the client C sends a call acceptance message CN5 to the client B, in response to which the client B sends the call acceptance message CN6 to the client A, from which it is evident that the call has been accepted at the client C. The call acceptance messages CN5 and CN6 each also include the client address information for the client C. The information that the call has been accepted at the client C is now available in the client A, and the client address information for the client C is also available at the same time in the client A (as the calling client). On the other hand, the client address information for the client A is also available in the client C, so that the communication link K1 can be set up directly as the payload data link between the clients A and C. In the exemplary embodiments described with reference to Figures 1a, 1b, 1c and 1d, a plurality of call forwarding destinations can in each case be stored in the client B as the first client. In this case, one service can be associated with each of these call forwarding destinations. It is thus possible, for example to use the client C as the call forwarding destination, for speech communication links, while a client D (not illustrated here) can be used as the call destination for fax messages. This is dependent on the call signaling message RS1, in each case also including details about the service which is intended to be used by the intended communication link K1. In the client B one of those clients which is suitable for the service of the communication link Kl, is then selected as the destination client. The implementation of the feature "follow-me" in a directly- communicating communication network will be explained in the following text with reference to the Figures 2a and 2b. In the case of follow-me, a call is signaled not only to a called terminal (client) but at the same time also to at least one further client. In this case, the call can be received at any of the clients to which this call is signaled. Figures 2a and 2b show the clients A, B, C which are already known from Figures 1a to 1d. In a first variant of the embodiment of follow-me, which will be explained with reference to Figure 2a, the designation and the client address information for the client C, as the destination client for follow-me, are stored by a user in the client B as the first client. In order to set up a communication link, the client A sends call signaling messages RS1 to the client B. The client B starts to signal the call ("the client B rings") and also sends further call signaling messages RS5 to the client C as the destination client, with the calling client A being indicated, with his client address information in the call signaling message RS5 in precisely the same way as in the call signaling message RS1. On the basis of the received call signaling message RS5, the call from the client A is now also signaled to the client C with a call acceptance message, which includes the client address information for the client C, being sent from the client C to the client B on acceptance of the call at the client C, and being passed on from the client B to the client A. After reception of this call acceptance message by the client A, the communication link is set up between the client A as the calling client and the client C. Alternatively, after acceptance of the call at the client C, the call acceptance message can also be transmitted directly from the client C to the client A. When the call which is signaled at the same time to the client B and the client C is accepted at the client B instead of the client C, the client B sends a call signaling cancellation message to the client C, after whose reception at the client D the call signaling to the client C is stopped, and the client B also sends a call acceptance signaling message to the client A, which includes the client address information for the client C, and after whose reception the client A sets up a communication link between the client A and the client B. Figure 2b shows a second variant for implementation of the feature "follow-me". In this example as well, the client A is the calling client, the client B is the first client, and the client C is the destination client. In the same way, the information is stored in the client B that the client C should likewise signal each call which is signaled to the client B. For this purpose, the client address information for the client C is also stored in the client B. In order to set up a communication link the client A sends a call signaling message RS1 to the client B. The call is signaled to the client B, and at the same time the client B sends a follow-me signaling message RZ1 back to the client A. It is evident from this follow-me signaling message RZ1 that the call which was signaled from the client A to the client B is also intended to be signaled to the client C with its associated client address. After reception of this follow-me signaling message RZl, the client A sends a further call signaling message to the client C with this call signaling message including the information that this call is a call which has been connected from the client B. After reception of the call signaling message RS6, the call is also signaled to the client C. The signaling of the call is acknowledged both by client B and by the client C, in each case by means of an acknowledgment message (not illustrated here) to the client A. If the call is now accepted at the client C, the client C sends a call acceptance message to the client A, after whose reception the client A sends to the client B a control message to end the call initiated by the call signaling message RS1, and as a result of which the communication link is furthermore set up between the client A and the client C. Alternatively, the call which is signaled to the client B and to the client C at the same time can be answered by the client B, as a result of which the client B then sends a call acceptance message to the client A. In this case, the client A sends a control message to the client C in order to end the call initiated by the call signaling message (cancellation message) RS6, and the communication link is also set up between the client A and the client B. In the case of the follow-me methods, described with reference to Figures 2a and 2b, a plurality of follow-me destinations can also be defined in each case in the first client B. In this case, a call can optionally be signaled at more than two terminals (clients) as well; alternatively or additionally different services can also be associated with these follow-me destinations, in which case one or more appropriate destination client or clients can be selected by the client B as a function of the service which is in each case requested by the call signaling message RS1. Furthermore, the "sender" of the call signaling message RS1 can also be evaluated in the client B, so that only calls from selected calling clients are signaled to the further clients. The implementation of the feature "callback" in a directly- communicating communication network will be described in the following text with reference to Figures 3a, 3b, 3c and 3d. In this case, Figures 3a and 3b relate to callback for a busy subscriber, while Figures 3c and 3d relate to callback for a free subscriber who has not accepted a call within a previously selected maximum waiting time. In order to explain the process for "callback when busy", Figure 3a shows the client A as the destination client and the client B as the first client and at the same time as the calling client. The client B in this case has a communication link K2 with the client C, so that the client B is busy. The preparation for and implementation of a callback between the client A and the client B from Figure 3a will be described in the following text with reference to Figure 3b. In order to set up a communication link, the client A sends a call signaling message RS1a to the client B. Since the client B is busy because of the communication link K2 to the client C, the client B responds to the call signaling message RSla by sending a busy message BS1 to the client A. An indication is now provided at the client A that the desired (called) client B is busy. The user of the client A now enters a command on his terminal with the aim of initializing the callback process. This command results in the client A sending to the client B a callback request message RR1, which includes the name and client address information of the client A. The client A sends an acknowledgment message (not illustrated here) to the client A in order to acknowledge reception of the callback request message RR1. When the communication link K2 has ended, the client B sends a callback completion message RK1 to the client A, thus signaling to the client A that the callback which was prepared for with the callback request message RR1 can take place. The client address information for the client A which was transmitted with the callback request message RR1 to the client B and restored there is used in this case to send the callback completion message RR1. After reception of the callback completion message RK1, the client A sends to the client B a new call signaling message RS1b as a result of which the call from the client A is signaled to the client B, which is now no longer busy. Once the call has been accepted at the client B (this step is no longer illustrated in Figure 3b), the client B sends a call acceptance message to the client A, as a result of which the communication link is set up between the client A and the client B. Figures 3c and 3d illustrate the process of callback to a free subscriber with Figure 3c showing the arrangement in which the client A is the destination client and the client B is the first client, and is at the same time a calling client. The interchange of the signaling messages relating to this between the client A and the client B is illustrated schematically in Figure 3d. As can be seen from Figure 3d, the client A sends a first call signaling message RS1a to the client B in order to set up a communication link. As a result of this call signaling message RSla, the call is signaled to the client B and the client B sends a call acknowledgment message AL1 ("alerting") to the client A as an acknowledgment message. A maximum time TO2 (in this case 20 seconds) is stored in the client A, and defines the maximum time period for call signaling of a call originating from the client A. If the call has not been accepted by the client B within this maximum time T02, the client A sends to the client B the callback request message RR1 which, in addition to the request for callback, also includes the client address information for the client A. This callback request is stored in the client B together with the received client address information of the client A. The process of carrying out the callback from the client B to the client A makes sense, of course, only when a user is present at the client B for whom the communication link could be intended. The terminal which forms the client B thus waits for a corresponding event which could indicate the presence of a natural person. In this case, this is the pressing of any key on the user interface of the client B. Any other event which can be detected by a technical device that is connected to the client B may, of course, also be used for this purpose. Once this event has been entered, a callback completion message RK1 is sent from the client B to the client A, as a consequence of which the client A sends to the client B a new call signaling message RSlb. After reception of the call signaling message RSlb, the call is signaled to the client B, in which case, after the call has been accepted, an appropriate call acceptance message (not illustrated any further here) is sent from the client B to the client A and this also results in the communication link being established between the client A and the client B. In this case, it should be noted that the call signaling and thus the setting up of the call originate from the client A both in the case of the call signaling message RS1a and in the case of the further call signaling message RSlb, so that the client A is debited with the payment of the charges, even in the case of the callback, charges which should generally always be debited to the originally calling client. In the case of the abovementioned exemplary embodiments it may be advantageous if a call to a client need not be explicitly accepted by a user. For this purpose, the call signaling messages are used to signal to a called client a "message" command, which results in the call signaling being suppressed and the called client being switched directly either to a "replay" mode (receive/replay) or to a completely active mode ("direct addressing" mode, transmission and reception). The "message" command can alternatively also be used to specify that a message which will be transmitted subsequently will not be replayed immediately, but after a defined time delay, at a specific time, or as a function of a specific event (pressing of a key, fire alarm, ending of an existing communication link, etc.) . Figures 4a and 4b show the signaling of a recorded message for a relevant client, and the calling of this stored message by the relevant client is described. The visualization (signaling) of a waiting message on the user interface of a client is also referred to as the "message waiting indication". First of all, the recording and the signaling of a message will be described with reference to Figure 4a. In order to set up a communication link, a client A sends a call signaling message RS1 to the client B, where the call is now signaled. However, the call is not answered at the client B, so that, once a previously defined waiting time TO1 (in this case 20 seconds) has elapsed, a control message (not illustrated here) is sent from the client A to the client B in order to end the call signaling (call cancellation message), this ending the call signaling to the client B. The user of the client A is now offered the option on the user interface to set up a link to a message store ("call answering service"), in order to store a message for the client B that cannot be reached. After confirmation by the user, the client A sets up a communication link to the client R, which is equipped with an appropriate memory unit SP1. In the present case, the client address information for the client R is permanently programmed in the client A; the client A may, of course, also have search functions by means of which one or more clients which have appropriate memory devices can be found in a directly communicating communication network. In this case, as in the previous examples, a distinction can possibly be drawn between different services, so that only speech memories("voice mail server") are looked for and used for speech links, and e-mail servers or the like are looked for and used for example for text messages. The client A uses the communication link K3 set up to the client R to store the message to be stored in the data memory SP1 of the client R and then sets up the link to the client R. After this, the client A sends to the client B, which is being used as the first client, a message waiting indication MWI1, which includes the client address information of the client R being used as the destination client, and an identification number for the message to be called up. The process of the client B, which in this case is being used as the called client, calling up the previously stored message will be explained in the following text with reference to Figure 4b. The user of the client B sees the information on the optical display of the user interface of the client B that a stored message from the client A can be called up. Once the user has entered a call-up command, the client B sends a specific call signaling message RSA to the client A in order to call up messages, with this call signaling message RSA including the identification number of the stored message intended for the client B. Furthermore, the call signaling message RSA includes the client address information for the client B. The communication link K4, via which the client R transmits the message stored in the data memory ST1 to the client B, is set up between the client B and the client R on the basis of the client address information interchanged in this way. The setting up and the clearing of a communication link from a waiting client to an information source for waiting information will be described in the following text with reference to Figure 5. In this case the waiting client can not only be supplied with waiting music or audio-based waiting information but it is also possible to provide, for example video messages or text-based information to the waiting user depending on the configuration of the client and the waiting information source. This feature is thus in general also referred to as "media on hold". In the initial state, the client A as the first client and the client B as the second client are connected to one another in a communication link K5a. This communication link K5a is assumed to have been temporarily interrupted by the client B. One possible reason for this is an inquiry from the client B and a further possible reason may be the intention of the client B to supply the client A with previously stored information. The last-mentioned application is typical of a call center, in which a caller is asking for specific information and this information is played back to the caller, initiated by a call center agent. In order to interrupt the communication link K5a and to start the information playback, the client B sends to the client A a call redirect signaling message RD2 (RD = redirect), which in addition to the "redirect" command includes the client address information for the client R that is intended to be the destination client. This client address information is stored in the client A, which is being used as the first client. Furthermore, the client B sends a message select signaling message MS1 (MS = message select) to the client R, in which the designation of that information which is intended to be made available to the client A is transmitted to the client R. The signaling message MS1 for this purpose also, of course, includes the client address information for the client A. The client R is equipped with the database SB2, in which a number of selectable information contents are stored in the form of files. As the calling client, the client A now sends signaling messages (not illustrated here) in order to set up a communication link K6 to the client A. This signaling message contains the client address information for the client A. In the client R, it is found that a message has already been selected for this client A, so that the client R sends a acknowledgement message "connect" (likewise, not illustrated here) to the client A, after whose reception the communication link K6 is set up. The communication link K6 is a monodirectional communication is set up. The communication link K6 is a monodirectional communication link, that is to say only a single data stream (data channel) is switched, specifically from the client R to the client A. Alternatively, the information relating to the selected message can also be transmitted from the client B to the client A. Once the communication link K6 has been set up, the client A then itself requests the message from the client R. In the present exemplary embodiment, this is waiting information which is transmitted by means of the communication link K6 from the client R to the client A, where it is reproduced. This waiting information is used to bridge the time period for an inquiry (not illustrated here) from the client B. Once this inquiry has been completed, the client B should end the replaying of the waiting music to the client A, and the interrupted communication link K5a should be resumed. For this purpose, the client B sends a signaling message RUl (connection transfer message) to the client A, which includes the client's address information for the client B and reference to the call redirect signaling message RD2. The client A therefore recognizes that the client B has the authorization to end the existing communication link K6 and to request the setting up of a "new" communication link K5b, which is used as a continuation of the interrupted communication link K5a. Together with the signaling message RUl, the client B sends to the client R a media control message MS2, in order to stop the replaying of the waiting information. After reception of the signaling message RUl the communication link K6 is ended by the client A, and the communication link K5b is set up between the client A and the client B. Alternatively, it is also possible to avoid sending the media control message MS2 from the client B to the client R in order to allow the communication link K5b to be interrupted once again by the client B at a later time, in order then to continue the replaying of the waiting information for the client A at the previously interrupted point. If the replaying of the waiting information is not carried out purely to bridge the waiting time but to provide specific information of the client A, it is advantageous to replay all of the selected waiting information to the client A. In this case, the link is not retrieved by the client B with the aid of the signaling message RU1 at an arbitrary time, and instead of this the client R then uses a signaling message "message complete" (not illustrated) to signal to the client B that the requested information has been replayed completely, in which case the client B does not initiate the clearing of the communication link K6 and the setting up of the communication link K5b to the client A until the "message complete" signaling message has been received. Temporary interruptions in the waiting information replay ("announcement") and thus in the communication link K6 are also possible, for example for a personal inquiry. This inquiry can be initiated either by sending appropriate signaling messages from the client B to the clients A and R, or by means of signaling messages which are sent from the client A to the clients B and R. Instead of completely interrupting the communication link K6, it is alternatively possible in the first-mentioned case to also "merge" the inquiry "softly" into the waiting information replay. For this purpose, specific control commands are transmitted with signaling messages transmitted by the client B leading to appropriate mixing of the waiting information with the inquiry in the client A. We Claim: 1. A method for setting up a communication link between two clients of a plurality of clients in a directly-communicating communication network, in which signaling information comprising client address information is interchanged between clients who wish to be involved in the communication link, in order to set up the communication link, the communication link is set up directly between the clients who wish to be involved in the communication link, on the basis of the client address information, characterized by the following method steps which carried out successively: a) a first communication link exists between a calling client and a second client, the client address information of a destination client being transmitted by the second client to the calling client, b) the first communication link is cleared c)the calling client uses this client address information to set up the communication link between the calling client and the destination client, and d) the communication link set up in step c) between the calling client and the destination client is taken down and the first communication link is set up again. 2. The method as claimed in claim 1, wherein the destination client is used as an information source for waiting times. 3. The method as claimed in claim 1 or 2, wherein several clients can be used as destination clients in the communication network, a destination client being selected as one of the suitable clients by the second client in step a). 4.The method as claimed in one of the preceding claims, wherein the calling client transmits call signaling information with a control command to the destination client when setting up the communication link in step c) so that the call is accepted automatically by the destination client. ABSTRACT TITLE: "A method for setting up a communication link between two clients of a plurality of clients in a directly communicating communication network" The invention relates to a method for setting up a communication link between two clients of a plurality of clients in a directly-communicating communication network, in which signaling information comprising client address information is interchanged between clients who wish to be involved in the communication link, in order to set up the communication link, the communication link is set up directly between the clients who wish to be involved in the communication link, on the basis of the client address information, following method steps which carried out successively a) a first communication link exists between a calling client and a second client, the client address information of a destination client being transmitted by the second client to the calling client, b) the first communication link is cleared c) the calling client uses this client address information to set up the communication link between the calling client and the destination client, and d) the communication link set up in step c) between the calling client and the destination client is taken down and the first communication link is set up again.

Full Text

FIELD OF THE INVENTION
The invention relates to a method for setting up a
communication link between two clients of a plurality of
clients in a directly-communicating communication network as
claimed in the precharacterizing clause of patent claim 1.
BACKGROUND OF THE INVENTION
Communication networks whose components communicate with one
another by packet switching are being used increasingly instead
of line-switching communication networks. Networks such as
these are frequently also referred to as Voice-Over-IP (VoIP)
networks, when the Internet Protocol (IP) is used to
interchange acoustic information (speech data) in the form of
data. In this case, the networks may either be used exclusively
for transmission of speech data or else can transmit both
speech data and other information (for example data, video) as
well in a mixed form.

In line-switching communication networks, terminals (for
example telephones, fax machines) are always connected to a
communication node (for example to a telephone system). The
entire information flow to and from the terminals in this case
takes place with the involvement of the respective
communication node, with control information, for example for
setting up links, being interchanged between the terminal and
the communication node, while the payload information (the
analog speech signal of the modulated fax signal) is admittedly
interchanged between the terminals that are involved in the
communication link but is passed on (transmitted) by at least
one communication node that is involved in the communication
link.
In speech data networks, the terminals are frequently referred

to as "clients", because the terminals in these communication
networks are operated in a similar manner to a computer in a
data network and not only as a telephone or fax machine, but
may also, for example be in the form of a multimedia PC. A
multimedia PC is a computer which has suitable hardware for
inputting information (for example a microphone, camera,
keyboard, scanner etc.) and for outputting information (for
example, a screen/display, loudspeakers, LEDs etc.). Clients
may also be in the form of a miniature PC (so-called PDA -
Personal Digital Assistant) or an extended mobile telephone
(smart phone). The appliances mentioned are often equipped with
a cordless data link and, in the case of mobile telephones are
then also referred to as "WLAN cellphones" (WLAN = Wireless
Local Area Network).
The clients in speech data networks generally interchange the
payload information directly with one another. For this
purpose, once a communication link has been set up, two clients
communicating with one another each interchange the data
packets with the payload information with the knowledge of the
network address of their communication partner, and on the
basis of these network addresses. In order to set up a link, by
contrast, central network nodes (communication nodes) are also
used in the known speech data networks. Network nodes such as
these are known to the speech data networks which use H.323
protocol (ITU-T-H.323) as "gatekeeper" and to the speech data
networks which use the SIP protocol (IETF-SIP; SIP = Session
Initiation Protocol), as SIP proxy servers.
Widespread data networks, in particular, the Internet, are
increasingly using communication structures which are referred
to as "peer-to-peer" networks or else "end-to-end" networks.
One primary field of application for communication structures
such as these is to interchange files, so-called "file
sharing". In this case, a subscriber (client) to a
communication structure such as this checks a number of other

clients (typically computers) when looking for a specific
resource (which may be a music file or a computer program) , and
starts to use this resource once it has been found, which
generally involves the transmission ("download") of one or more
files. In this case, either appropriate communication partners
(clients) are found using a database, or else the clients can
be found by appropriate communication methods without any
central instance.
Some of the known "peer-to-peer" networks are used for the
purpose of direct communication. The "media data" that is
interchanged in this case, that is to say the payload data, is
not restricted to speech (speech data) or modulated information
(for example fax transmissions), but also includes moving image
information (video transmission, video conferences, "multimedia
messaging") and other forms of electronic communication. In
communication networks such as these, which are also referred
to as "directly-communicating communication networks", this
means on the one hand that communication links can be set up in
the form of conventional "telephone calls", while on the other
hand it is also possible to transmit extended contents
("multimedia"). Avoiding the use of central network nodes
(communication nodes) in this case results in the advantage of
increased resistance to failures, although it is associated
with the disadvantage that the (switching) functionality of the
network nodes, as is known from line-switching telephony must
be provided by the clients involved in the communication link,
themselves.
The document US 2003/0095546 Al Sakano et al. "IP Telephone
terminal searching for destination with a telephone number to
set up a call connection over an IP network" has already
disclosed a directly communicating communication network in
which clients set up direct communication links with one
another using addresses (IP addresses). In this case it is
proposed to send a search message with a call number to

adjacent clients, whereby, in cases in which a client who
receives the search message is allocated this call number, this
client makes his IP address available to the first, searching
client in order to initiate a communication link on the basis
of the Internet protocol.
In the case of the known directly-communicating communication
networks, it has been found to be particularly disadvantageous
when a client must have the address information (for example
the network address) of a second client in order to set up a
communication link to that second client. This is a problem
because, in general, there is no network node (for example
communication server) directly associated with the client, with
which it is possible to check an address such as this. Even if
the address information for the desired communication partner
is known, it is possible in directly-communicating
communication networks that it is not possible to reach this
desired communication partner (for example if it is "busy" or

if the client has failed) so that, for example it is desirable
to set up a link to an alternative call destination
("alternative destination"). Since directly-communicating
communication networks do not use central network nodes for
storage of address information such as this, the problem of
addressing still exists when setting up a connection to an
alternative call destination such as this.
One object of the invention is to propose a method by means of
which the address information which is required for
communication links in directly-communicating communication
networks can be determined.
The object is achieved by the features of the invention, in that the following
method steps are carried out successively: first of all (step a) client
address information which is required to set up a communication
link between the clients in pairs is stored for at least one

destination client in a first client. Then (step b), the stored
client address information for the destination client is
transmitted from the first client to a calling client, and then
(step c) the calling client uses this client address
information to set up the communication link between the
calling client and the destination client. When the
abovementioned method steps are carried out, this results in a
calling client in the directly-communicating communication
network having transmitted to it the address of the destination
client that is required to set up a communication link, with
the link being set up without any access to a central
communication node or to a central address database. The fact
that call forwarding has been carried out can remain concealed
for the calling client if the destination client forms the call
forward destination for the first client in step a) , and when a
call arrives from the calling client, the first client sends
signaling information for call signaling of a further call to
the destination client in step b), in which case on acceptance
of the further call at the destination client, the latter
transmits a call acceptance signaling message to the first
client, on the basis of which the first client transmits the
client address information for the destination client to the
calling client. In this case the call forwarding is carried out
not only when the first client is busy but also in the case of
a call which is not accepted by the first client, in that the
signaling information for call signaling of the further call is
transmitted to the destination client if the call is not
answered at the first client within a waiting time. This
waiting time can advantageously be set or changed by a user at
the first client, by means of an input. The feature of "call
forwarding" can advantageously be made use of for this purpose
in the event of an unsuccessful call to a free subscriber
(client) in that the details about waiting time are stored in
the first client in step a) , and a call is signaled to the
first client in step b), on the basis of the received signaling
information, and the stored client address information is

transmitted to the calling client only if the call to the first client is not answered
within the waiting time.
The method allows features to be provided in a directly-communicating
communication network without the inclusion of a central switching instance, in
which case, as a further advantage, the lack of a central communication node or
of a central subscriber directory results in a high degree of operational reliability
and availability in the communication network because, in the event of a failure
of one communication component (dient) only a relatively small portion of the
communication network is affected. Furthermore, communication networks which
use the method according to the invention can be extended more easily and can
be scaled better.
Call forwarding can be set up and carried out in a simple manner and in that in
order to forward a call, the destination client forms the call forward destination
for the first client in step a), and the calling client sends signaling information for
call signaling to the first client between steps a) and b), in order to set up a
communication link.
In the case of call-forwarding, a user at the first claim can enter various call-
forwarding destinations, with a suitable one of the call forwarding destinations
being selected depending on the nature (service) of the call arriving at tiie first
client or of the communication link that is intended with the call. This is achieved
in that the client address information for a plurality of destination clients is stored
in the first client in step a), and is in each case associated with one or more
different services, and when call arrives at the first

client, the signaling information in step b) defines the
service which is intended to be supported by the communication
link to be set up, with the client address information for that
destination client which is associated with this service being
selected and transmitted on the basis of this definition. In
this case, the services are advantageously selected from a
group which comprises at least speech services, video services
and data services.
The method according to the invention allows a call to be
signaled to a plurality of clients at the same time and to be
answered at any desired one of these clients in that the
destination client is provided as the follow-me destination in
step a), the calling client sends signaling information for
call signaling to the first client between steps a) and b) in
order to set up a communication link, and the call signaling
takes place both at the first client and at the destination
client in step c) in that the calling client sends further
signaling information for call signaling to the destination
client with the communication link being set up between the
calling client and the destination client when the call is
accepted at the destination client.
In the case of follow-me, it is possible to avoid a situation
in which the calling client sends signaling information to a
plurality of clients, in that, in this case as well, the
destination client is provided as the follow-me destination in
step a) , between steps a) and b), the calling client sends
signaling information for call signaling to the first client in
order to set up a communication link, and the call signaling
takes place both at first client and at the destination client,
in that the first client sends further signaling information
for call signaling of a further call to the destination client,
with the destination client sending a call acceptance message
to the first client after acceptance of this call, and the
first client also transmitting the call reception message with

the client address information of the destination client to the
calling client in step b).
The method allows the feature of "callback" to be provided in a
simple manner in a directly-communicating communication
network, in that in order to prepare for a callback, in
situations in which an incoming call from the destination
client to the first client is not accepted in step a) , the
destination client stores the client address information
together with the callback information in the first client, and
in order to carry out the callback in step b) the first client,
as the calling client, requests the destination client to carry
out the callback. In this case, the callback when the client is
busy is requested in that step a) is carried out when the first
client is in the busy state and, the callback is made when the
busy state of the first client no longer exists. In contrast to
this, a callback can also be requested in the case of a client
which is not busy and to which a call has been signaled unsuc-
cessfully in that step a) is carried out when the incoming call
has not been accepted at the first client within a waiting
time, and the callback is completed when an event which
reflects the presence of a user is detected at the first
client. An event such as this advantageously does not need to
be an explicit reaction by a user to a callback request, so
that the callback is initialized with as short a time delay as
possible, for example when a person returns to his desk.
Various non-central message stores (speech boxes, video stores,
e-mail system, etc.) can be used in directly-communicating
communication networks in that in order to record and to call a
message which is intended for the first client,
before step a), a second client sets up a communication link to
the destination client with the message being stored in the
destination client, after step a) the presence of the stored
message is signaled to the first client, in step b) in turn,
the calling client is formed by the first client, and in step

c) the stored message is called up at the destination client
using the communication link. In this case, various services
can be used in the communication network, in which case a
plurality of recording clients for storage of messages are
available in the communication network, and, before step a) the
second client selects a suitable one of the recording clients
as the destination client. In this case, in each case at least
one type of recordable message is advantageously associated
with the recording client in which case, in step a) in each
case one recording client is selected which is appropriate for
the type of message to be recorded.
In the event of a brief interruption in an existing
communication link, for example for questions, it is
advantageous for a subscriber (client) who is waiting during
the interruption to be supplied with information (for example
waiting music, product information, etc.). This can be achieved
in that a first communication link exists between the first
client and the second client in step a) , with the client
address information for the destination client being
transmitted by the second client to the first client, the first
client forms the calling client in step b), and the first
communication link is cleared after step b), and after step c),
the communication link which was set up in step c) between the
calling client and the destination client is cleared, and the
first communication link is set up again. In this case, the
destination client is advantageously used as the information
source for waiting times.
Before the interruption of the first communication link, a user
of the second client can decide which contents and which type
of media (speech, images, text information, etc.) should be
output to the first client during the waiting time. This is
achieved in that a plurality of clients can be used as the
destination client in the communication network, with one of
the usable clients being selected as the destination client by

the second client in step a) . In this case, the destination
client can advantageously be in the form of an instance on the
same hardware, which forms the basis for the first or for the
second client.
In a directly-communicating communication network,
announcements can be emitted to clients in a simple manner, in
which case a client who is receiving the announcement can be
activated automatically without a user having to do anything in
that in step c) the calling client, when setting up the
communication link, transmits call signaling information along
with a control command to the destination client so that the
call is automatically accepted by the destination client.
Exemplary embodiments of the method according to the invention
will be explained in the following text with reference to the
drawings, in which:
Figures 1a, 1b show the interchange of signaling information
between clients in a directly-communicating
communication network, for the purpose of call
forwarding when free,
Figures 1c, 1d show the interchange of signaling information
for call forwarding when busy,
Figure 2a shows an arrangement of clients in a directly-
communicating communication network for
provision of follow-me in a first variant,
Figure 2b shows the interchange of signaling information
for the implementation of follow-me in a second
variant,
Figure 3a shows the initiation of a callback for a busy
client,

Figure 3b shows the interchange of signaling information
for initiation and for carrying out a callback
for a busy client,
Figure 3c shows the signaling of a call for a free (not
busy) client,
Figure 3d shows the signaling information for the
initiation and for carrying out a callback for a
free client,
Figure 4a shows the storage of a message for a client and
the signaling of a stored message for this
client,
Figure 4b shows the calling up of the stored message by
the notified client, and
Figure 5 shows the supply of a client with waiting
information while a communication link is on
hold.
Figure la shows a schematic illustration of clients A, B, C who
are arranged in a directly-communicating communication network
(not illustrated) . The clients A, B, C in this and in the
following exemplary embodiments are in the form of multimedia
PCs which set up communication links with one another in a
packet-switching communication network (IP network; IP =
Internet Protocol) by interchanging signaling information
(control messages) with one another. These control messages are
represented as arrows in the figures with the direction of the
arrow in each case indicating the direction of the information
flow of the respective control message. In this case, a multiple
data interchange can take place between the clients interchanging
the control message in order to interchange said control message,

for example in order to acknowledge reception of the control
message in a so-called "handshake process". In the case of the
communication links between the clients as illustrated
schematically in the figures, there is in each case a logic
relationship between two clients, with data packets with payload
information being transmitted between the clients on the basis of
previously interchanged client address information. The payload
information may optionally be speech information (speech data) or
other contents (for example, video information, text
information), and mixed forms of the various types of information
(these are also referred to as "services") are possible.
The clients, control messages and communication links which are
known from Figure la and from the following figures are also
used repeatedly in other figures with the same reference
symbols. These are then clients, control messages and
communication links with essentially the same functions, and
are therefore not described again in the description of the
further figures.
Instead of the multimedia PCs that were used as clients in the
figures, it is also possible to use any other desired
components intended for communication, for example telephony
terminals (IP telephones, VoIP telephones; VoIP = Voice-over
Internet Protocol), fax machines, etc. The significant factor
for the clients described here is that they are designed for
operation in directly-communicating communication networks,
that is to say their function and interaction with other
clients and devices in a communication network take place
without the use of a central instance, for example a
communication node or a central server. This principle is still
applicable when the functionality of a client is not sufficient
to carry out a specific task, and this client therefore
appoints a proxy to carry out the functionality that it is
missing.

The implementation of the feature "call forwarding" with the
aid of the method according to the invention will be described
in the following text with reference to Figures 1a, 1b, 1c and
1d, with Figures la and lb showing call forwarding in the case
of a call to a free subscribe and Figures 1c and 1d showing
call forwarding in the case of a call to a busy subscriber.
In Figure la, a user of the client B as the first client has
determined with an input that all calls which reach his
terminal (client B) will be forwarded to the client C as the
destination client after a waiting time TO1 (TO = Time Out) of
20 seconds if the call is not accepted at the client B within
this waiting time TOl. Let us assume that a communication link
is intended to be set up to a client B from the client A as the
calling client. For this purpose, the client A sends a call
signaling message RSI to the client B, which initiates call
signaling (the client B "rings") at the client B. At the same
time the client B sends an acknowledgment message AL1
("alerting") to client A as acknowledgment. The call is not
accepted at the client B, so that the waiting time TOl times
out.
The client B now sends a call redirect message RD1 (RD =
Redirect) to the client A, which instructs the client A now to
signal the call which was signaled to the client B to the
client C as the destination client. The call redirect message
RD1 in this case comprises the client address information for
the client C, which has been entered by the user during his
definition of the client C as the call forwarding destination.
The signaling of the call to the client B is now stopped, and
the client A, as the calling client, sends further call
signaling information RS2 to the client C, after whose
reception the client C starts to signal the call, and in
response to which the client C sends an acknowledgment message
AL2 ("alerting") to the client A for acknowledgment. Once the
call has been accepted at the client C, the client C sends a

call acceptance signaling message CN1 ("connect"), to the
client A in response to which the communication link Kl
(payload data link) is established between the client A and the
client C.
As a further example of call forwarding when free, Figure lb
once again shows the waiting time TO1 being carried out in the
client B as the first client by a user, and the client address
information for the client C being defined as the call
forwarding destination (destination client) for calls to the
client B which are not accepted. In this case as well, a call
from the client A to the client B takes place with the aid of
the call signaling message RS1, with this call once again being
acknowledged by the acknowledgment message AL1, and with the
waiting time TOl also passing in this case without the call
having been accepted at the client B. In contrast to the
process described with reference to Figure la, the client B now
ceases to signal the call and now uses a further call signaling
message RS3 to the client C which, in addition to the command
to signal a call to the client C, also includes the additional
information that this call is a forwarded call from the client
A. The call is now signaled to the client C, and an
acknowledgment message AL3 is sent to the client B. Whilst the
client C has accepted the call, the client C sends a call
acceptance message CN3 to the client B in response to which the
client B sends a further call acceptance message CN4 to the
client A as the calling client, including the information that
the call being signaled on the basis of the call signaling
message RS1 has been forwarded to the client C, where it has
been accepted. This call acceptance message CN4 also includes
the client address information for the destination client,
client C, so that the communication link K1 is now set up
between the client A and the client C.
Figure 1c shows call forwarding when busy, in a first variant.
At the client B as the first client, a user defines the client

C as the destination client for call forwarding when busy. In
this case, the client address information for the destination
client C is also stored in the client B. The client A now sends
call signaling messages RS1 to the client B which, however, is
already busy with a further communication link, which is not
illustrated here. On the basis of the stored information, the
client B now sends a call redirect message RD2 (for call
forwarding) to the client A, including the designation and the
client address information for the client C as the destination
client, and also including the information that the client B is
busy and that this call will thus be forwarded to the client C.
As the calling client, the client A now sends further call
signaling information RS2 to the client C, by which means the
call is signaled to the client C, and the acknowledgment
message AL2 is sent to the client A. After acceptance of the
call at the client C, the client C sends out call acceptance
message CN1 to the client A, after whose reception the
communication link K1 is set up between the client A and the
client C.
Figure 1d also shows the signaling messages which are
interchanged between the clients A, B, C in order to carry out
call forwarding when busy. In this variant as well, the name
and the client address information for the client C as the
destination client for call forwarding when busy are stored in
the client B as the first client. Client A now once again sends
call signaling messages RS1 to the client B, with the client B
also being busy in this case and not itself signaling the call.
The client B now sends further call signaling messages RS4 to
the client C, from which call signaling message it is evident
that the call is the call which originated from the client A.
In this case, the client address information for the client A,
which is transmitted with the call signaling message RS1 to the
client B, is also passed to the client C. The call is now
signaled to the client C with this fact being signaled by means
of the acknowledgment message AL4 from the client C to the

client B. After reception of the acknowledgment message AL4,
the client B sends an acknowledgment message AL5 to the client
A, from which it is evident that the call that was initiated by
the call signaling message RS1 has been forwarded to the client
C and is now being signaled to the client C. After acceptance
of the call at the client C, the client C sends a call
acceptance message CN5 to the client B, in response to which
the client B sends the call acceptance message CN6 to the
client A, from which it is evident that the call has been
accepted at the client C. The call acceptance messages CN5 and
CN6 each also include the client address information for the
client C. The information that the call has been accepted at
the client C is now available in the client A, and the client
address information for the client C is also available at the
same time in the client A (as the calling client). On the other
hand, the client address information for the client A is also
available in the client C, so that the communication link K1
can be set up directly as the payload data link between the
clients A and C.
In the exemplary embodiments described with reference to
Figures 1a, 1b, 1c and 1d, a plurality of call forwarding
destinations can in each case be stored in the client B as the
first client. In this case, one service can be associated with
each of these call forwarding destinations. It is thus
possible, for example to use the client C as the call
forwarding destination, for speech communication links, while a
client D (not illustrated here) can be used as the call
destination for fax messages. This is dependent on the call
signaling message RS1, in each case also including details
about the service which is intended to be used by the intended
communication link K1. In the client B one of those clients
which is suitable for the service of the communication link Kl,
is then selected as the destination client.
The implementation of the feature "follow-me" in a directly-

communicating communication network will be explained in the
following text with reference to the Figures 2a and 2b. In the
case of follow-me, a call is signaled not only to a called
terminal (client) but at the same time also to at least one
further client. In this case, the call can be received at any
of the clients to which this call is signaled.
Figures 2a and 2b show the clients A, B, C which are already
known from Figures 1a to 1d. In a first variant of the
embodiment of follow-me, which will be explained with reference
to Figure 2a, the designation and the client address
information for the client C, as the destination client for
follow-me, are stored by a user in the client B as the first
client. In order to set up a communication link, the client A
sends call signaling messages RS1 to the client B. The client B
starts to signal the call ("the client B rings") and also sends
further call signaling messages RS5 to the client C as the
destination client, with the calling client A being indicated,
with his client address information in the call signaling
message RS5 in precisely the same way as in the call signaling
message RS1. On the basis of the received call signaling
message RS5, the call from the client A is now also signaled to
the client C with a call acceptance message, which includes the
client address information for the client C, being sent from
the client C to the client B on acceptance of the call at the
client C, and being passed on from the client B to the client
A. After reception of this call acceptance message by the
client A, the communication link is set up between the client A
as the calling client and the client C.
Alternatively, after acceptance of the call at the client C,
the call acceptance message can also be transmitted directly
from the client C to the client A.
When the call which is signaled at the same time to the client
B and the client C is accepted at the client B instead of the

client C, the client B sends a call signaling cancellation
message to the client C, after whose reception at the client D
the call signaling to the client C is stopped, and the client B
also sends a call acceptance signaling message to the client A,
which includes the client address information for the client C,
and after whose reception the client A sets up a communication
link between the client A and the client B.
Figure 2b shows a second variant for implementation of the
feature "follow-me". In this example as well, the client A is
the calling client, the client B is the first client, and the
client C is the destination client. In the same way, the
information is stored in the client B that the client C should
likewise signal each call which is signaled to the client B.
For this purpose, the client address information for the client
C is also stored in the client B. In order to set up a
communication link the client A sends a call signaling message
RS1 to the client B. The call is signaled to the client B, and
at the same time the client B sends a follow-me signaling
message RZ1 back to the client A. It is evident from this
follow-me signaling message RZ1 that the call which was
signaled from the client A to the client B is also intended to
be signaled to the client C with its associated client address.
After reception of this follow-me signaling message RZl, the
client A sends a further call signaling message to the client C
with this call signaling message including the information that
this call is a call which has been connected from the client B.
After reception of the call signaling message RS6, the call is
also signaled to the client C. The signaling of the call is
acknowledged both by client B and by the client C, in each case
by means of an acknowledgment message (not illustrated here) to
the client A. If the call is now accepted at the client C, the
client C sends a call acceptance message to the client A, after
whose reception the client A sends to the client B a control
message to end the call initiated by the call signaling message

RS1, and as a result of which the communication link is
furthermore set up between the client A and the client C.
Alternatively, the call which is signaled to the client B and
to the client C at the same time can be answered by the client
B, as a result of which the client B then sends a call
acceptance message to the client A. In this case, the client A
sends a control message to the client C in order to end the
call initiated by the call signaling message (cancellation
message) RS6, and the communication link is also set up between
the client A and the client B.
In the case of the follow-me methods, described with reference
to Figures 2a and 2b, a plurality of follow-me destinations can
also be defined in each case in the first client B. In this
case, a call can optionally be signaled at more than two
terminals (clients) as well; alternatively or additionally
different services can also be associated with these follow-me
destinations, in which case one or more appropriate destination
client or clients can be selected by the client B as a function
of the service which is in each case requested by the call
signaling message RS1. Furthermore, the "sender" of the call
signaling message RS1 can also be evaluated in the client B, so
that only calls from selected calling clients are signaled to
the further clients.
The implementation of the feature "callback" in a directly-
communicating communication network will be described in the
following text with reference to Figures 3a, 3b, 3c and 3d. In
this case, Figures 3a and 3b relate to callback for a busy
subscriber, while Figures 3c and 3d relate to callback for a
free subscriber who has not accepted a call within a previously
selected maximum waiting time.
In order to explain the process for "callback when busy",
Figure 3a shows the client A as the destination client and the

client B as the first client and at the same time as the
calling client. The client B in this case has a communication
link K2 with the client C, so that the client B is busy.
The preparation for and implementation of a callback between
the client A and the client B from Figure 3a will be described
in the following text with reference to Figure 3b. In order to
set up a communication link, the client A sends a call
signaling message RS1a to the client B. Since the client B is
busy because of the communication link K2 to the client C, the
client B responds to the call signaling message RSla by sending
a busy message BS1 to the client A. An indication is now
provided at the client A that the desired (called) client B is
busy. The user of the client A now enters a command on his
terminal with the aim of initializing the callback process.
This command results in the client A sending to the client B a
callback request message RR1, which includes the name and
client address information of the client A. The client A sends
an acknowledgment message (not illustrated here) to the client
A in order to acknowledge reception of the callback request
message RR1.
When the communication link K2 has ended, the client B sends a
callback completion message RK1 to the client A, thus signaling
to the client A that the callback which was prepared for with
the callback request message RR1 can take place. The client
address information for the client A which was transmitted with
the callback request message RR1 to the client B and restored
there is used in this case to send the callback completion
message RR1. After reception of the callback completion message
RK1, the client A sends to the client B a new call signaling
message RS1b as a result of which the call from the client A is
signaled to the client B, which is now no longer busy. Once the
call has been accepted at the client B (this step is no longer
illustrated in Figure 3b), the client B sends a call acceptance
message to the client A, as a result of which the communication

link is set up between the client A and the client B.
Figures 3c and 3d illustrate the process of callback to a free
subscriber with Figure 3c showing the arrangement in which the
client A is the destination client and the client B is the
first client, and is at the same time a calling client. The
interchange of the signaling messages relating to this between
the client A and the client B is illustrated schematically in
Figure 3d.
As can be seen from Figure 3d, the client A sends a first call
signaling message RS1a to the client B in order to set up a
communication link. As a result of this call signaling message
RSla, the call is signaled to the client B and the client B
sends a call acknowledgment message AL1 ("alerting") to the
client A as an acknowledgment message. A maximum time TO2 (in
this case 20 seconds) is stored in the client A, and defines
the maximum time period for call signaling of a call
originating from the client A. If the call has not been
accepted by the client B within this maximum time T02, the
client A sends to the client B the callback request message RR1
which, in addition to the request for callback, also includes
the client address information for the client A. This callback
request is stored in the client B together with the received
client address information of the client A.
The process of carrying out the callback from the client B to
the client A makes sense, of course, only when a user is
present at the client B for whom the communication link could
be intended. The terminal which forms the client B thus waits
for a corresponding event which could indicate the presence of
a natural person. In this case, this is the pressing of any key
on the user interface of the client B. Any other event which
can be detected by a technical device that is connected to the
client B may, of course, also be used for this purpose. Once
this event has been entered, a callback completion message RK1

is sent from the client B to the client A, as a consequence of
which the client A sends to the client B a new call signaling
message RSlb. After reception of the call signaling message
RSlb, the call is signaled to the client B, in which case,
after the call has been accepted, an appropriate call
acceptance message (not illustrated any further here) is sent
from the client B to the client A and this also results in the
communication link being established between the client A and
the client B. In this case, it should be noted that the call
signaling and thus the setting up of the call originate from
the client A both in the case of the call signaling message
RS1a and in the case of the further call signaling message
RSlb, so that the client A is debited with the payment of the
charges, even in the case of the callback, charges which should
generally always be debited to the originally calling client.
In the case of the abovementioned exemplary embodiments it may
be advantageous if a call to a client need not be explicitly
accepted by a user. For this purpose, the call signaling
messages are used to signal to a called client a "message"
command, which results in the call signaling being suppressed
and the called client being switched directly either to a
"replay" mode (receive/replay) or to a completely active mode
("direct addressing" mode, transmission and reception). The
"message" command can alternatively also be used to specify
that a message which will be transmitted subsequently will not
be replayed immediately, but after a defined time delay, at a
specific time, or as a function of a specific event (pressing
of a key, fire alarm, ending of an existing communication link,
etc.) .
Figures 4a and 4b show the signaling of a recorded message for
a relevant client, and the calling of this stored message by
the relevant client is described. The visualization (signaling)
of a waiting message on the user interface of a client is also
referred to as the "message waiting indication".

First of all, the recording and the signaling of a message will
be described with reference to Figure 4a. In order to set up a
communication link, a client A sends a call signaling message
RS1 to the client B, where the call is now signaled. However,
the call is not answered at the client B, so that, once a
previously defined waiting time TO1 (in this case 20 seconds)
has elapsed, a control message (not illustrated here) is sent
from the client A to the client B in order to end the call
signaling (call cancellation message), this ending the call
signaling to the client B. The user of the client A is now
offered the option on the user interface to set up a link to a
message store ("call answering service"), in order to store a
message for the client B that cannot be reached. After
confirmation by the user, the client A sets up a communication
link to the client R, which is equipped with an appropriate
memory unit SP1.
In the present case, the client address information for the
client R is permanently programmed in the client A; the client
A may, of course, also have search functions by means of which
one or more clients which have appropriate memory devices can
be found in a directly communicating communication network. In
this case, as in the previous examples, a distinction can
possibly be drawn between different services, so that only
speech memories("voice mail server") are looked for and used
for speech links, and e-mail servers or the like are looked for
and used for example for text messages. The client A uses the
communication link K3 set up to the client R to store the
message to be stored in the data memory SP1 of the client R and
then sets up the link to the client R. After this, the client A
sends to the client B, which is being used as the first client,
a message waiting indication MWI1, which includes the client
address information of the client R being used as the
destination client, and an identification number for the
message to be called up.

The process of the client B, which in this case is being used
as the called client, calling up the previously stored message
will be explained in the following text with reference to
Figure 4b. The user of the client B sees the information on the
optical display of the user interface of the client B that a
stored message from the client A can be called up. Once the
user has entered a call-up command, the client B sends a
specific call signaling message RSA to the client A in order to
call up messages, with this call signaling message RSA
including the identification number of the stored message
intended for the client B. Furthermore, the call signaling
message RSA includes the client address information for the
client B. The communication link K4, via which the client R
transmits the message stored in the data memory ST1 to the
client B, is set up between the client B and the client R on
the basis of the client address information interchanged in
this way.
The setting up and the clearing of a communication link from a
waiting client to an information source for waiting information
will be described in the following text with reference to
Figure 5. In this case the waiting client can not only be
supplied with waiting music or audio-based waiting information
but it is also possible to provide, for example video messages
or text-based information to the waiting user depending on the
configuration of the client and the waiting information source.
This feature is thus in general also referred to as "media on
hold".
In the initial state, the client A as the first client and the
client B as the second client are connected to one another in a
communication link K5a. This communication link K5a is assumed
to have been temporarily interrupted by the client B. One
possible reason for this is an inquiry from the client B and a
further possible reason may be the intention of the client B to

supply the client A with previously stored information. The
last-mentioned application is typical of a call center, in
which a caller is asking for specific information and this
information is played back to the caller, initiated by a call
center agent.
In order to interrupt the communication link K5a and to start
the information playback, the client B sends to the client A a
call redirect signaling message RD2 (RD = redirect), which in
addition to the "redirect" command includes the client address
information for the client R that is intended to be the
destination client. This client address information is stored
in the client A, which is being used as the first client.
Furthermore, the client B sends a message select signaling
message MS1 (MS = message select) to the client R, in which the
designation of that information which is intended to be made
available to the client A is transmitted to the client R. The
signaling message MS1 for this purpose also, of course,
includes the client address information for the client A. The
client R is equipped with the database SB2, in which a number
of selectable information contents are stored in the form of
files.
As the calling client, the client A now sends signaling
messages (not illustrated here) in order to set up a
communication link K6 to the client A. This signaling message
contains the client address information for the client A. In
the client R, it is found that a message has already been
selected for this client A, so that the client R sends a
acknowledgement message "connect" (likewise, not illustrated
here) to the client A, after whose reception the communication
link K6 is set up. The communication link K6 is a
monodirectional communication is set up. The communication link
K6 is a monodirectional communication link, that is to say only
a single data stream (data channel) is switched, specifically
from the client R to the client A.

Alternatively, the information relating to the selected message
can also be transmitted from the client B to the client A. Once
the communication link K6 has been set up, the client A then
itself requests the message from the client R.
In the present exemplary embodiment, this is waiting
information which is transmitted by means of the communication
link K6 from the client R to the client A, where it is
reproduced. This waiting information is used to bridge the time
period for an inquiry (not illustrated here) from the client B.
Once this inquiry has been completed, the client B should end
the replaying of the waiting music to the client A, and the
interrupted communication link K5a should be resumed. For this
purpose, the client B sends a signaling message RUl (connection
transfer message) to the client A, which includes the client's
address information for the client B and reference to the call
redirect signaling message RD2. The client A therefore
recognizes that the client B has the authorization to end the
existing communication link K6 and to request the setting up of
a "new" communication link K5b, which is used as a continuation
of the interrupted communication link K5a. Together with the
signaling message RUl, the client B sends to the client R a
media control message MS2, in order to stop the replaying of
the waiting information.
After reception of the signaling message RUl the communication
link K6 is ended by the client A, and the communication link
K5b is set up between the client A and the client B.
Alternatively, it is also possible to avoid sending the media
control message MS2 from the client B to the client R in order
to allow the communication link K5b to be interrupted once
again by the client B at a later time, in order then to
continue the replaying of the waiting information for the
client A at the previously interrupted point.

If the replaying of the waiting information is not carried out
purely to bridge the waiting time but to provide specific
information of the client A, it is advantageous to replay all
of the selected waiting information to the client A. In this
case, the link is not retrieved by the client B with the aid of
the signaling message RU1 at an arbitrary time, and instead of
this the client R then uses a signaling message "message
complete" (not illustrated) to signal to the client B that the
requested information has been replayed completely, in which
case the client B does not initiate the clearing of the
communication link K6 and the setting up of the communication
link K5b to the client A until the "message complete" signaling
message has been received.
Temporary interruptions in the waiting information replay
("announcement") and thus in the communication link K6 are also
possible, for example for a personal inquiry. This inquiry can
be initiated either by sending appropriate signaling messages
from the client B to the clients A and R, or by means of
signaling messages which are sent from the client A to the
clients B and R. Instead of completely interrupting the
communication link K6, it is alternatively possible in the
first-mentioned case to also "merge" the inquiry "softly" into
the waiting information replay. For this purpose, specific
control commands are transmitted with signaling messages
transmitted by the client B leading to appropriate mixing of
the waiting information with the inquiry in the client A.

We Claim:
1. A method for setting up a communication link between two clients of a
plurality of clients in a directly-communicating communication network,
in which signaling information comprising client address information is
interchanged between clients who wish to be involved in the communication
link, in order to set up the communication link,
the communication link is set up directly between the clients who wish to be
involved in the communication link, on the basis of the client address
information, characterized by
the following method steps which carried out successively:
a) a first communication link exists between a calling client and a second
client, the client address information of a destination client being transmitted
by the second client to the calling client,
b) the first communication link is cleared
c)the calling client uses this client address information to set up the
communication link between the calling client and the destination client, and
d) the communication link set up in step c) between the calling client and the
destination client is taken down and the first communication link is set up
again.

2. The method as claimed in claim 1, wherein the destination client is used as an
information source for waiting times.
3. The method as claimed in claim 1 or 2, wherein several clients can be used as
destination clients in the communication network, a destination client being
selected as one of the suitable clients by the second client in step a).
4.The method as claimed in one of the preceding claims, wherein the calling
client transmits call signaling information with a control command to the
destination client when setting up the communication link in step c) so that the
call is accepted automatically by the destination client.

ABSTRACT

TITLE: "A method for setting up a communication link between two clients of a
plurality of clients in a directly communicating communication network"
The invention relates to a method for setting up a communication link between
two clients of a plurality of clients in a directly-communicating communication
network, in which signaling information comprising client address information is
interchanged between clients who wish to be involved in the communication link,
in order to set up the communication link, the communication link is set up
directly between the clients who wish to be involved in the communication link,
on the basis of the client address information, following method steps which
carried out successively a) a first communication link exists between a calling
client and a second client, the client address information of a destination client
being transmitted by the second client to the calling client, b) the first
communication link is cleared c) the calling client uses this client address
information to set up the communication link between the calling client and the
destination client, and d) the communication link set up in step c) between the
calling client and the destination client is taken down and the first
communication link is set up again.

Documents:

00156-kolnp-2008-abstract.pdf

00156-kolnp-2008-claims.pdf

00156-kolnp-2008-correspondence others.pdf

00156-kolnp-2008-description complete.pdf

00156-kolnp-2008-drawings.pdf

00156-kolnp-2008-form 1.pdf

00156-kolnp-2008-form 2.pdf

00156-kolnp-2008-form 3.pdf

00156-kolnp-2008-form 5.pdf

156-KOLNP-2008-(02-04-2012)-CORRESPONDENCE.pdf

156-KOLNP-2008-(02-04-2012)-ENGLISH TRANSLATION.pdf

156-KOLNP-2008-(09-09-2011)-PETITION UNDER RULE 137.pdf

156-KOLNP-2008-(13-08-2012)-CORRESPONDENCE.pdf

156-KOLNP-2008-CANCELLED PAGES.pdf

156-KOLNP-2008-CORRESPONDENCE 1.1.pdf

156-KOLNP-2008-CORRESPONDENCE.pdf

156-KOLNP-2008-EXAMINATION REPORT.pdf

156-kolnp-2008-form 18.pdf

156-KOLNP-2008-GRANTED-ABSTRACT.pdf

156-KOLNP-2008-GRANTED-CLAIMS.pdf

156-KOLNP-2008-GRANTED-DESCRIPTION (COMPLETE).pdf

156-KOLNP-2008-GRANTED-DRAWINGS.pdf

156-KOLNP-2008-GRANTED-FORM 1.pdf

156-KOLNP-2008-GRANTED-FORM 2.pdf

156-KOLNP-2008-GRANTED-FORM 3.pdf

156-KOLNP-2008-GRANTED-FORM 5.pdf

156-KOLNP-2008-GRANTED-SPECIFICATION-COMPLETE.pdf

156-KOLNP-2008-OTHERS.pdf

156-KOLNP-2008-PA.pdf

156-KOLNP-2008-REPLY TO EXAMINATION REPORT.pdf

abstract-00156-kolnp-2008.jpg

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Patent Number

257990

Indian Patent Application Number

156/KOLNP/2008

PG Journal Number

48/2013

Publication Date

29-Nov-2013

Grant Date

25-Nov-2013

Date of Filing

10-Jan-2008

Name of Patentee

SIEMENS ENTERPRISE COMMUNICATIONS GMBH & CO. KG.

Applicant Address

HOFMANNSTRASSE 51, 81379 MUNCHEN

Inventors:

#	Inventor's Name	Inventor's Address
1	RALF NEUHAUS	FRIEDRICH-WILHELM-WEBER-STRASSE 22M, 44534 LUNEN
2	RAINER UECKER	VONSCHEIDTS HOF 21 45470 MULHEIM

PCT International Classification Number

H04L 29/06

PCT International Application Number

PCT/EP2004/010474

PCT International Filing date

2004-09-17

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10345072.6	2003-09-26	Germany