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From: jay@splut.conmicro.com (Jayyou ignorant splut! Maynard)
Newsgroups: comp.dcom.telecom
Subject: Re: Touchtone History
Message-ID: <9790@accuvax.nwu.edu>
Date: 16 Jul 90 11:44:02 GMT
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Reply-To: Jay "you ignorant splut!" Maynard <jay@splut.conmicro.com>
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In article <9706@accuvax.nwu.edu> drivax!marking@uunet.uu.net writes:

>) It was probably a Department of Defense phone. These phones looked
>) like touch-tone, made noises *similar* to touch-tone, but were on the
>) private DOD Autovon network.

>Each of the buttons makes two tones, one based on row and one based on
>column, selected so as not to be harmonics of each other. (Hence
>*Dual* Tone Multi Frequency.) The frequencies are:
>			1209	1336	1477	1653 Hz
>		697 Hz	 1	 2	 3	 A
>		770 Hz	 4	 5	 6	 B
>		852 Hz	 7	 8	 9	 C
>		941 Hz	 *	 0	 #	 D
>Most phones don't use the last column, but CCITT defines it.

You'll find that almost all amateur radio DTMF keypads have the fourth
column in place; those tones are extensively used for remote control
purposes on amateur VHF/UHF-FM.

The DOD keypads did use the standard CCITT DTMF tones. I know of
several hams who have surplus four-column DOD keypads, and use them
interchangeably with the regular kind. They're nice, too, being
backlit and easy to see in the dark. The fourth column is labeled
Fo/F/I/P instead of A/B/C/D, for Flash Override, Flash, Immediate, and
Priority.  Instead of * and #, it has a five-pointed star (general
priority? :-) and A (no idea what this one's for).


Jay Maynard, EMT-P, K5ZC, PP-ASEL   
jay@splut.conmicro.com