Path: utzoo!utgpu!watmath!att!tut.cis.ohio-state.edu!brutus.cs.uiuc.edu!wuarchive!texbell!vector!telecom-gateway
From: euatdt@euas11g.ericsson.se (Torsten Dahlkvist)
Newsgroups: comp.dcom.telecom
Subject: Re: DTMF Frequencies From a Musician's Point of View
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Date: 14 Aug 89 06:20:13 GMT
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Reply-To: Torsten Dahlkvist 
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X-TELECOM-Digest: volume 9, issue 297, message 2 of 8

In article  optilink!jones@ames.arc.
nasa.gov (Marvin Jones) writes:

>Perhaps the more musically useful Telecom tone is precise (digital) dial tone,
>which uses 350 and 440 Hz. The higher of these tones is US standard concert A
>(middle A).  There have been many times I have been away from home, or other
>source of musical reference, and have picked up a phone to get an "A" to
>help tune a guitar or keyboard.

Beware, though, that if you leave the U.S you may well find yourself in one
of the "sine dial-tone" countries which output a single sine wave tone of
nominally 421 Hz. Because of the wide tolerances specified for this frequency,
440 Hz is actually within the limits and many old exchanges were in fact
"tuned" to this standard A. Nowadays, however, admins are getting stuffier
and as exchanges are getting modernized they usually get re-tuned to 421 Hz.

/Torsten

 Torsten Dahlkvist                        ! "I am not now, nor have I ever
 ELLEMTEL Telecommunication Laboratories  !  been, intimately related to
 P.O. Box 1505, S-125 25  ALVSJO, SWEDEN  !  Dweezil Zappa!"
 Tel: +46 8 727 3788                      !        - "Wierd" Al Yankowitz