TAD PORT

11/10/2001

TAD Port: Two somewhat different ports may be encountered that use the acronym TAD. Telephone Answering Device Ports are simple (RJ-11) phone plugs backed up by possibly elaborate switching logic. Telephone Audio Device ports are simple four pin ports with single mono audio in and out connections on pin 1 and 4. Pins 2 and 3 are grounded. Obviously, the two types of TAD port are incompatible.

Telephone Answering Device TADs are found on telephone routing devices that attempt to automatically route incoming phone calls to FAX devices, modems and/or answering machines. When an answering machine is included, the device must deal with the possibility that the answering machine may be either on or off. Typical processing might be that the router detects an incoming call, picks up, and puts a ring signal onto the TAD port. Meanwhile it generates artificial ring tones to give the incoming call the illusion that the line has not been picked up. If the TAD picks up the line, the router stops the fictitious ring tones and drops off the line leaving the caller connected to the TAD. If the TAD does not pick up in a reasonable time, the router will route the call elsewhere.

Without the TAD port(s), it would often be necessary to move wires when configuring an answering machine on line at night, and again in the morning to get the answering machine out of the system. TADs are also used to allow optional routing based on caller ID.

When a computer is connected to a phone router that has a TAD port, the TAD port will probably get preference over the "Modem" port in handling incoming calls. It may help in establishing connections if the calling modem uses a "/R" in its initialization string. That will cause the calling modem to put up a tone without waiting for the receiving end to pick up (remember that the receiving end is trying hard to look like it hasn't picked up). That tone may cause the router to route the call to its modem port rather than to the TAD port.

The "TAD Port" on sound cards is not the same as the TAD port on a phone router. Sound card TAD ports appear to be intended to allow the sound card to act as a telephone answering or telephone voice communication Device.

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