Called ID

Caller ID system is a feature of digital telephone network, which allows the telephone number of the caller to be transferred to the called person before he/she answers the phone. This feature can be useful for example for storing numbers of the people who have tried to call you when you were not home. In completely digital systems (like ISDN and GSM) send the caller ID information as part of normal completely digitla signaling.

After digitialization of PSTN network (all parts except last mile are digital) this caller ID functionality is become available in PSTN network also. There are two different commonly used caller ID signalling systems for sending caller ID informationg using normal telephone line (PSTN). Bellcore system (which is used in USA) send the numer in data packet which is sent at 1200 bps speed using FSK-modem. Eropean system send the same information using standard DTMF (Dual Tone Multi Frequency) signalling.

Useful Links

• Caller ID circuits and information - information and circuits for different systems used USA and Finland
• Caller ID Links - lots of links to web Sites related to caller ID
• Caller Identification - What Standards are Involved?
• Computer Caller ID FAQ
• FCC Caller ID page - general info nad FAQ
• Frequently Asked Questions About Caller-ID
• FX602 Calling Line Identifier IC - for deconding called ID systems used in USA and UK, datasheet has example circuits
• Guidelines for implementation caller ID service in Finland (GFI9702) - information about DTMF based caller ID system in use in Finland

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Useful links

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