Path: utzoo!attcan!uunet!seismo!sundc!pitstop!texsun!convex!killer!vector!nobody From: imp@crayview.msi.umn.edu (Chuck Lukaszewski) Newsgroups: comp.dcom.telecom Subject: Re: DTMF vs. Touch-Tone Message-ID: Date: 25 Dec 88 20:37:57 GMT Sender: chip@vector.UUCP Lines: 16 Approved: telecom-request@vector.uucp X-Submissions-To: telecom@bu-cs.bu.edu X-Administrivia-To: telecom-request@vector.uucp X-TELECOM-Digest: volume 8, issue 209, message 4 In article , prindle@NADC.ARPA (Frank Prindle) writes: > I'm curious when the term DTMF (Dual Tone Multi Frequency) became synonymous > with Touch Tone. As I recall, DTMF once designated the set of dual-tone > frequencies used for in-band signaling on long distance trunks, which used > a completely different set of tones than Touch Tone, and was always generated Actually, DTMF has always been generated by premises telephones. The in-band signalling to which you refer was done with single MF tones which were on 200-Khz frequency multiples. The DTMF tones, by contrast, are combinations of highly unique frequencies to minimize the potential of duplicating them though nature (or something like that - it's been a while). The whole blue box thing got started when the Bell System Technical Journal published a paper which happened to contain the actual MF signalling frequencies. ______________________________________________________________________________ Chuck Lukaszewski imp@crayview.msi.umn.edu 612 789 0931