|Title of Invention||
"A CALL IDENTIFICATION SYSTEM"
|Abstract||A call identification system comprising a call identification and display means, provided along with the called party telephone system, call processing subsystem interconnected to a peripheral sub-system consisting of dual tone multi frequency resource (7) and micro controller (1) to convert the calling party digits into equivalent Dual Tone multi-frequency tones, being outpulsed into the analog loop of PSTN (Public Switch Telephone Network) lines, wherein the said PSTN (Public Switch Telephone Network) lines are decoded and processed by the said call identification system and displayed on to the said display means (8),|
|Full Text||The present invention relates to a Calling line Identification system for Telephone
Calling line ID, with its supporting hardware and software, supplies the subscriber with the capability to identify who is making an incoming call by either displaying the incoming caller's telephone number, or the incoming caller's name and number. It is known that Caller ID is transmitted as a burst of a Bell (Frequency Shift Key) modem signal between the first and second ringing cycles. Therefore the subscribers should always wait for the second ring to get the identification. Otherwise, the early pickup causes loss of data. According to the Bellcore TR-NWT-000030 the Central Office physical layer interface should support Continuous-phase binary Frequency Shift Keying with 1200 band as the transmission rate Similarly the Caller ID display Customer Premises Equipment should have special purpose devices that can support the proposed Bellcore standard. These changes may not be implemented inexpensively in all the switches.
The objective of the invention is to obviate the above difficulties and implement the Caller ID related technologies inexpensively and with an equal case.
The invention lies in the implementation of Signaling scheme adopted for Caller ID transmission and the design of Caller ID display device. The transmission of Caller ID is in dual tone multifrequency tones. In general most of the Switching systems will have either multi frequency or dual tone multi frequency resources. These resources can be fully exploited for the transmission of Caller ID by introducing the necessary software changes at the Central Office. These software changes can easily be implemented in a typical Stored Program Controlled Switching system.
The Caller ID display device designed as a Customer Premises Equipment uses inexpensive Dual tone multi frequency receivers and line interface devices that can be used to interface with the above implementation. According to the invention of Dual
tone multi frequency signaling for the Caller ID, the implementation of Caller ID technologies is carried out as follows:
To avail this facility the customers should get themselves registered for Caller ID facility at the exchange. Subsequent to this, the calls to subscribers of Caller ID, the terminating switch obtains the Caller ID and an indication of the privacy (Private or Public) status of the Caller ID during the basic Call setup.
After the subscribers register themselves at the exchange office, the exchange operators will give CLI feature by using the administrative subsystem of the exchange software. In the call analysis the call processing subsystem of the exchange software determines whether called party has the CLI feature or not. In case the called party has the CLI feature, then the call processing sub-system collects the digits. In case of line to line call, the calling party digits are locally available in the exchange system itself. In case of Inter-exchange call, the terminating exchange will request the exchange for the calling party digits. This is possible in case of MF signalling schemes. After collecting the calling party digits, the call processing sub-system will pass on the digits to the peripherl sub-system.
The exchange system used for this feature is divided into three subsystems:-
1. ADMIN Subsystem
This is responsible for providing CLIP and CLIM facilities to the subscribers. These facilities are used by the switch operators to extend the Caller ID feature to the subscribers.
2. PERIPHERAL Subsystem
This is responsible for sending Caller ID in the form of Dual Tone Multifrequency (DTMF) tones to the subscriber lines. For this, the existing DTMF resources Switching systems are fully exploited. The DTMF controller that is already existing in the switch is responsible for generating the DTMF tones of Caller ID onto the subscriber lines. The DTMF controller gets digits from Call Processing software. The
controller will first place a start signal (DTMF ) and Caller ID tones and a stop signal (DTMF) as a terminating signal. The tone duration is 50 msec and intertone gap is 50 msec.
3 CALL PROCESSING (CP) Subsystem
This is responsible for collecting Calling party ID during Call Processing phase. In the present system has been implemented Calling number delivery to the customer premises. If a call is originated form the same exchange where the Caller ID subscriber is terminated, then, the exchange will be having the Calling party number. The CP subsystem will allocate a DTMF resource and sends the Calling digits as a message to the DTMF controller. The DTMF controller will send all the digits as DTMF tones to the Called subscriber and an ACK message will be sent to the CP subsystem. The CP subsystem will then de-allocate the DTMF resource and instructs the Terminal Interface Controller to send the ringing current to the called subscriber having Caller ID feature.
In case the Call is coming from some other exchange and the interoffice signaling if MF (Multifrequency) the terminating exchange will request Automatic Number Identification system from the originating exchange for the Calling party number.
The CP subsystem then executes the same steps as explained in the above paragraph. In case of unavailability of the Caller ID number the CP will not allocate DTMF resource and it will instruct the TIC to drive the ringing cycle to Caller ID subscriber. This situation is interpreted by the Caller ID display CPE (Customer Premises Equipment) as No Number case. Similar approaches have been implemented for SS7 signaling.
Caller ID display device
This section explains the Caller ID display unit designed as a Customer Premises Equipment. This unit can receive DTMF tones sent by the CO, on ON HOOK and OFF HOOK conditions of the telephone instrument. For Caller ID display and
storage, the CPE expects DTMF transmission on On Hook and for Call Waiting feature it expects the DTMF transmission on OFF HOOK condition.
START DTMF tone will alert the CPE to receive process, display and store the subsequent DTMF Caller ID digits. The last STOP DTMF tone is an indication to terminate the reception of DTMF digits. Subscribers can see the Caller ID before ringing. The CPE provides the required termination, provides high voltage isolation, detects ringing, detects battery reversal, detects 16 khz metering pulse, and converts the coded DTMF digits into serial data format which is required for PC interface.
The following are the functional specifications of CLI device:
CALLING NUMBER DISPLAY:
CLI displays the calling number at the called subscriber premises. The number will be displayed through out the conversation phase and throughout th ringing phase in case of no reply condition. This number can be fed to PC for data base applications.
CALLING NUMBER STORAGE:
CLI stores the in-coming calling numbers up to 08. This feature enables the users to know the identities of the calling subscribers in the absence of called subscribers. Subscribers can know the most recently stored numbers by pressing NUM switch. In case a particular number gets repeated for several times storing will be done once and the display indicates calling number and the number of times it occured.
DIALED NUMBER DISPLAY:
Display indicates the digits dialed irrespective of DTMF or DECADIC instruments. No storage in this case is done, however the dialed number can be stored in the PC which is connected to ESSU. This number will be cleared after receiving the subsequent battery reversal and 16KHZ pulse. This dialed number can be fed to the PC for data base applications.
DURATION OF CONVERSATION AT THE CALLING END:
Display indicates the duration of conversation in hours, minutes and seconds. For this the battery reversal is taken as a reference. The changing information can be fed to PC for accumulated data base of charged units.
DISPLAY OF CHARGING UNITS:
For this 16khz pulse detection circuit output is the reference.
This is a special feature provided in CLI, with this the user can interface a PC (windows loaded) and can have database for CID, metering, dialed number display etc. CLI interfaces the computer to the telephone through a interface.
This allows the display of calling number when 2 parties are in conversation. This is displayed for 5 seconds.
The following is the general description of various sections of CLI:
Line Interface Section:
Line interface section has been designed to satisfy the following requirements of
1) Protection from the ringing voltage 60 Vrms to 120 Vrms: This has been
implemented by selecting high values of resistors and diodes.
2) Protection from high voltage transient surges: Secondary protection against high
voltage surges due to lightening, induction or contact with foreign potential. This is
incorporated by making use of gas discharge tube.
3) Phone line termination: Microcontoller is used to control the relay which in turn is
used to control the impedance offered to the line. During the calling number
receiving mode the relay is energised so as to satisfy termination requirement by
setting the port line low. In all other cases the relay is de-energised so as to offer very high impedence by setting the port line high.
DC Loop Detection :
The loop detection is implemented in an inexpensive way . This section is responsible for detecting ON- HOOK and OFF-CONDITIONS. ON-HOOK is indicated if the DC current across the loop is less then 8-10 mA. OFF-HOOK condition is indicated when the loop current exceeds the current of the loop.
Battery Rversal Indication:
Two outputs generated by loop-detection logic are used by micro-controller to monitor the battery reversal across the TIP and RING. This is used for the indication of duration at the calling end.
Ring Detection Section:
Ring detection has been implemented in an in-expensive way by using opto-isolators, resistor and capacitor network. The first ring is taken as a refernce to display the calling number.
CLI- PC interface is established by making use of several port interface of microcontroller using driver and receiver for this application.
METERING DETECTION LOGIC
Private metering detection 1C has been used for 16Khz pulse detection. The port line of micro controller is used for monitoring MET DET line of 16Khz pulse detection logic. The units for the current call should be added to the cumulative units.
DTMF RECEIVER SECTION
The DTMF detection is carried out by a receiver which is configured under differential mode. After receiving a valid DTMF tone the receiver will assert STD pin which is connected to INT. This will enable the micro controller to execute a service
routine which reads the DTMF code generated by DTMF receiver and converts the code into an ASCII format suitable for LCD display.
The main controller used in CL1 for control operations. The port pin is used for detecting ON HOOK, OFF HOOK and DECADIC pulse detection. High level on this line indicates OFF HOOK and low indicates ON HOOK.
For the DECADIC pulse display the MAKE period and BREAK needs to be validated. Ring chatter creates a pulsing activity on this line during ringing. Programmer should not validate this line during ringing.
The port pin is used for stored calling number display request.A high on this line indicates a request for stored number display. Upon receiving high signals the program should start displaying the most recently received numbers on last come first served display bases.
RESET OPERATION (RESET)
Both manual and power-one reset operation has been incorporated.The reset should clear the display and initialise the LCD.
Port is used for ring detection indication RD. A high on the line indicates presence of ring. The first ring is taken as a reference to display the calling number. The R DET is generated by monoshot which is designed for a pulse width. The ring pulse generated by last ON pulse of the ring will occupy of the silence period of the power ring. Because of this reason another active ring occurring afterwords will be treated as a new ring of the another call. Other wise program will treat the ring as continuation of the pervious ring.
A port line is used for monitoring pulse detection logic output line indicating the validity of the presence of the metering pulse. The units display program will count
the member of units and displays it on real time basis. The units for the current call will be added to the cumulative units.
The port line is used as an output line to control the relay. The relay is energised so as to satisfy resistance termination requirement by setting the port line low. In all the cases the relay is de-energised so as to offer very high impedance by setting the port line high.
The port lines are used to monitor the battery reversal operation used for duration of conversation and metering. In the battery reversal condition these port lines assumes different logical levels. The program will monitor these lines and take an appropriate actions.
By setting the port line DTMF receiver can be put in power down mode so as to reduce the power dissipation. Whenever there is no DTMF detection is utilised.
The port is used to reset number display latch after recognising a high signal on P14 so as to accept next request.
An additional port is used as an output port line. This line satisfies the necessary handshaking required for Register Select signal of LCD module. For all the commands and addresses this signal is high and for data this is low.
Switches RST, NUM and MET are used for reset, number display and accumulated retering display operations.
ESSU has one DC socket for holding the DC supply.
POWER DOWN OPERATION
The powerdown operation is implemented by a microcontroller. In case of failure an interrupt is generated so that the service routine will interrupt microcontroller to backup the RAM contents. When the microcontroller is in power down mode the. battery will feed supply to the microcontroller.
CL1 has an interface with Personal Computer. The dialed nos. metering information and caller IDs are sent to PC through this interface. Personal Computer based database management can be developed by this.
The present invention relates to a call identification system comprising a call identification and display means , provided along with the called party telephone system, calling processing subsystem interconnected to a peripherl sub-system consisting of dual tone multi frequency resourceand controller to convert the calling party digits into equivalent Dual Tone multi-frequency tones, being outpulsed into the analog loop of PSTN lines, wherein the said PSTN lines are decoded and processed by the said calling line identification device and displayed on to the said display means.
BRIEF DESCRIPTION OF THE DRAWING:
Fig. 1 refers to the flow diagram of the working of calling line identification device.
DETAILED DESCRIPTION OF THE DRAWING:
The Microcontroller (1) controls the relay which in turn controls the impedance offered to the line. This microcontroller (1) is attached with the DC Loop Detection (2) which indicates the on-hook and off-hook conditions and monitor the battry reversal (3) for the indication of duration at the calling end. Opto-isolators, resistors anfd capacitotr making an Ring -detection centre (4) displays the calling number. The POTS Line Interface (5) further have metering detection unit (6) for monitoring
MET-DET line. DTMF receiver section (7) connected to the POTS Line Interface (5) enables the micro-controller (1) to execute a service routine which reads the DTMF code generated by DTMF receiver and converts the code into an ASC II format suitable for LCD display. (8).The converted DTMF tones will be outpulsed onto the analog loop of the PSTN lines. The nalog DTMF tones will be outpulsed at the Tone duration of 50msec. and having Inter tone gap as 50 m sec. The tones corresponding to the calling party are decoded and processes by the calling line identification device and displayed onto the LCD display . The CLI can also be fed to the PC for other computer based applications.
The Caller ID technologies can easily be implemented by making use of proposed DTMF signaling scheme for Caller ID transmission scheme. This signaling scheme will in turn simplify the design of Caller ID display device CPE. This system shall find extensive usage in essential services such a police, fire Ambulance and the like where caller's identification is required-
1) A call identification system comprising a call identification and display means , provided along with the called party telephone system, calling processing subsystem interconnected to a peripherl sub-system consisting of dual tone multi frequency resource and controller to convert the calling party digits into equivalent Dual Tone multi-frequency tones, being outpulsed into the analog loop of PSTN lines, wherein the said PSTN lines are decoded and processed by the said calling line identification device and displayed on to the said display means.
2) A call identification system as claimed in claim 1, wherein the said call processing sub-system of the exchange software have detection means to find out whether called party has the Calling Line Identification device or not.
3) A call identification system as claimed in claim 1, wherein the peripherl sub¬system comprises Dual Tone multi-frequency resource and controller to programme and DTMF resorce to convert the calling party digits into equivalent DTMF tones.
4) A call identification system as claimed in claim 1, wherein the said display means are either liquid crystal display (LCD) or Personal Computer.
5) A call identification system as claimed in claim 1, wherein the Calling Line Identification is provided with memory device to store the incoming calls.
6) A call identification system as claimed in claim 1, wherein the means are provided
for display the calling numbers in case the line is busy.
7) A call identification system as claimed in claim 1, wherein the said means are
Calling Line Identification operable by meand of a NUM Switch.
8) A call identification system herein described with reference to the accompanying
|Indian Patent Application Number||2258/DEL/1996|
|PG Journal Number||08/2008|
|Date of Filing||17-Oct-1996|
|Name of Patentee||CENTRE FOR DEVELOPMENT OF TELEMATICS|
|Applicant Address||9th FLOOR, AKBAR BHAWAN, CHANKYAPURI, NEW DELHI-110021, INDIA.|
|PCT International Classification Number||NA|
|PCT International Application Number||N/A|
|PCT International Filing date|