Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request From: Eric Smith Newsgroups: comp.dcom.telecom Subject: Re: A New Feature One Might Build Into a Phone Message-ID: <11022@accuvax.nwu.edu> Date: 17 Aug 90 20:41:17 GMT Sender: news@accuvax.nwu.edu Organization: Frobozz Magic Widget Company Lines: 34 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 10, Issue 579, Message 9 of 9 In article <10948@accuvax.nwu.edu> U5434122@ucsvc.ucs.unimelb.edu.au writes: > In article <10715@accuvax.nwu.edu>, synsys!jeffj@uunet.uu.net writes: > > I'll go you one better: right after the tritone (that's called a SIT, > > right?), transmit the data DIGITALLY with a modem, the same FSK as > > used in Caller-ID. > Rather than using a modem, DTMF signalling could be used. It is not > as fast, but what's an extra couple of seconds, when you don't have to > wait for the modems to CONNECT? Using a FSK modulation doesn't imply a need for modems to handshake a connection, as is done with 212 and V.22bis modems. There is not really any advantage to using DTMF, and it is MUCH slower, and would delay the voice recording enough to be annoying. > Modems already have tone senders in them. A tone interpreter should > not be too difficult, and the modem could inform the controlling > software with messages like 'TONE 1' or 'TONE *' etc. Putting a DTMF tone decoder into a typical modem would requre the addition of an IC (such as an SSI 204), while many modems already have FSK demodulator chips that are capable of handling the required freqencies, even though the modem may not utilize the particular frequencies in its normal operation. This is common because there are general purpose modem chips which handle many standards. Eric L. Smith Opinions expressed herein do not necessarily reflect those esmith@apple.com of my employer, friends, family, computer, or even me! :-)