How does Caller ID work?
A. In contrast to how Caller ID works over a plain ordinary telephone service (POTS) line, where it is delivered as a V.23 modem signal between the 1st and 2nd ring cycles, Caller ID over an ISDN line is delivered over the D (signaling) channel at the initial onset of call setup in compliance with ITU-T specification Q.81.3. However, ISDN Caller ID will not contain any time stamp information. The LAN Modem, in processing the Caller ID signal, superimposes its own internal clock (date and time) signal and outputs the combined information to the POTS port(s) as a V.23 signal, allowing conventional Caller ID display units to function. This information, like an ordinary POTS line, is generated between the 1st and 2nd rings. If the time displayed with the call is incorrect it is because the LAN Modem’s internal clock is incorrect and since the LAN Modem gets its date and time info from the workstation, it is likely that the workstation’s date and time is incorrect.
A. Caller ID works over a plain ordinary telephone service (POTS) line, where it is delivered as a V.23 modem signal between the 1st and 2nd ring cycles. In most cases, you need to subscribe to the Caller ID service from your phone company. They may charge a fee for this service. If you have subscribed to the Caller ID service, but the Caller ID box attached to the LAN Modem is not displaying the Calling Party’s number then you should contact your phone company. For more information on Caller ID, take a look at Testmark’s white paper.
