Path: utzoo!utgpu!watmath!att!bellcore!texbell!vector!telecom-gateway From: morris@jade.jpl.nasa.gov (Mike Morris) Newsgroups: comp.dcom.telecom Subject: Re: DTMF Frequencies Message-ID: Date: 7 Aug 89 07:12:21 GMT Sender: news@vector.Dallas.TX.US Reply-To: Mike Morris Lines: 32 Approved: telecom-request@vector.dallas.tx.us X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@vector.dallas.tx.us X-TELECOM-Digest: volume 9, issue 279, message 4 of 9 (Rick Watson) writes: > >What are the frequencies of the various tones used for DTMF? > 1209 1336 1477 1633 697 1 2 3 A FO 770 4 5 6 B F 852 7 8 9 C I 941 * 0 # A D P I have an old 5-line 4-wire Autovon phone here that I modified (added a network) for 25-pair 2-wire use. It has a "A" on the key that would normally be a "#". The 4th column keys are labeled with FO-F-I-P. On another Tiwanese throw-away phone I've seen the same keys labeled A-B-C-D, this phone was sold at the local K-Mart and the extra buttons were explained as "4 additional keypad keys for future banking and special services". A long time ago I figured out the mathematical sequence that the frequencies follow - Without overlapping the groups I figured that you could get a 9 by 9 matrix, with overlap a 12 by 9 (my memory is hazy, this would have been in 1969 or 1970). Note that these are not "MultiFreq" tones. Mike Morris UUCP: Morris@Jade.JPL.NASA.gov #Include quote.cute.standard | The opinions above probably do not even come cat flames.all > /dev/null | close to those of my employer(s), if any.