Hi Lerameur,
In the alarm business our dialers call a receiver that gives a series or handshake tones. For example, the first tone might be 1800hz for 1 sec, if no reply from the dialer within 2 secs, then a 1400hz tone for 1 sec, wait for a response, if none then another tone is sent consisting of 1/2 second of 1400 then 1/2 second of 1800, wait for a response, if none then one or two more speciality handshake tones are sent before the receiver gives up and hangs up. Each different handshake tone tells the receiver what type of data format the dialer is using to send the information. Newer receivers use DSP processors and algorithims to determine the data format based on the number of digits, interdigit spacing, and the frequency of the data. One type of receiver recognizes the caller ID of the incoming call and issues only one type of handshake/kissoff tone that it knows that specific dialer needs.
If your dialer is calling you or someone specific, why not spice up your project and use a voice chip like Emic, Speakjet, or one of the ISD chips to deliver short message that instructs the person receiving the call to press 1 or * or # when they hear the message. This would let your dialer know that it reached someone.
At http://www.clare.com/Products/callprogress.htm They have what are called "Call Progress chips". Teltone used to make them but I didn't see anything about them on their site. They analize the progress of the call for you and interface to uC's.
If you need anymore information on the alarm dialers let me know. I have written courses on them for the alarm industry in the past.
HTH,
BobK
Bookmarks