baller@cbnewsi.att.com (eric.h.baller) (07/11/90)
Has anyone decoded touch-tones off a phone line? Modems can generate them, but I haven't seen any that can read them. I know there are things like the Complete Answering Machine around for $300, but has anyone hacked up (or bought) something better (cheaper, mostly). All it needs to do is tell me which key they hit. Any pointers MUCH appreciated, Eric Baller AT&T Bell Laboratories (supply net access, not opinions) [this isn't for at&t] (201) 949-4285 (soon to be area code 908) ehb@erebus.att.com
grege@gold.GVG.TEK.COM (Greg Ebert) (07/12/90)
In article <1990Jul10.220135.22660@cbnewsi.att.com> baller@cbnewsi.att.com (eric.h.baller) writes: >Has anyone decoded touch-tones off a phone line? >Modems can generate them, but I haven't seen any that can read them. > If you're a hardware type, you can build decoder with a DTMF decoder chip. It will give you a 4-bit code. The chip is made by OKI (MSM6843).
cgordon@vpnet.chi.il.us (Gordon Hlavenka) (07/17/90)
>Has anyone decoded touch-tones off a phone line?
There are many ICs which do this. I know Radio Shucks sells one for around
$10. The chip runs on a color burst crystal (3.58-ish MHz) and produces hex
output from audio input. Use an isolation transformer with a series cap on
the phone line side to grab the audio. Be sure to put some clamping in
there! An incoming ring is 90 - 130 vac!
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Gordon S. Hlavenka cgordon@vpnet.chi.il.us
Disclaimer: He's lyingefb@suned1.Nswses.Navy.MIL (Everett F Batey) (05/05/91)
If you want all the wisdom, move your question to comp.dcom.telecom. THere are numerous mfgrs of TT Decoder chips. Heavily used in amateur radio, could post there, too. THere are some SIGs in USENIX that have done presentos on tt ifcs for telephone .. voicemail .. etc. You only need to find the right forum and you will get barraged (sp?) .. folks all over you. -- + efb@suned1.nswses.Navy.MIL efb@gcpacix.uucp efb@gcpacix.cotdazr.org + + efb@nosc.mil WA6CRE Gold Coast Sun Users Vta-SB-SLO DECUS gnu + + Opinions, MINE, NOT Uncle Sam_s | b-news postmaster xntp dns WAFFLE +