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From: julian@bongo.uucp (Julian Macassey)
Newsgroups: comp.dcom.telecom
Subject: Re: Touchtone History
Message-ID: <9616@accuvax.nwu.edu>
Date: 11 Jul 90 13:06:52 GMT
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X-Telecom-Digest: Volume 10, Issue 475, Message 5 of 9


In article <9533@accuvax.nwu.edu>, johns@scroff.uk.sun.com (John
Slater) writes:

> In article <9482@accuvax.nwu.edu>, roy@alanine.phri.nyu.edu (Roy
> Smith) writes:

> >Sitting on the table behind his chair were
> >about 3 or 4 single line desk sets, one touch-tone, the rest rotary.

> Er, shouldn't that be "one push-button, the rest rotary"?  Unless you
> heard the tones when JFK made a call, it could just be a
> pulse-dialler.  In the UK, push-button pulse-dialling phones have been
> around for years, long before touch-tone came along.

	No, it shouldn't. Because the Brit public was exposed to nasty
"Push-to-Pulse" phones before touch-tone does not mean that is the
history of the technology.

	From a UK perspective, I had a Plessey touch-tone phone in
1979-80.  It now resides in the Macassey garage and junk store
alongside a push-to-pulse "warble-phone". In the UK, touch-tone has
been available on TXE-4, System-X and AXE-10 exchanges. On the TXE-4
exchange you have to ask them to turn it on. Yes dear U.S. readers,
it's free.  British Telecom has not promoted touch-tone in the U.K.
Many U.K.  residents seeing touch-tone phones on TV have assumed they
were push-to-pulse. A couple of years ago my brother in law wandered
into the Canterbury British Telecom phone store and asked to buy a
touch-tone or "MF" phone. The assistant was not sure what he wanted so
called a technician. He told my brother in law that touch-tone was
"Not available, and doesn't work here." I send him touch-tone phones
from the US that work just fine on his TXE-4 exchange.

	Anyhow, touch-tone in the U.S. The early push-button phones in
the U.S. were all touch-tone. The early dials had only 10 buttons - no
* and #. They produced tones with "plucked reeds". I have never
examined one of these, just seen pictures, they must have been
mechanical nightmares. Later versions used LC oscillators using a
transistor and pot core coils. These dials had several contacts for
muting, row and column etc. The latest dials use an IC and a color TV
crystal (3.58 Mhz) as the frequency element. The IC dials have fewer
switch contacts (one set per digit) than the old dials so are cheaper
to manufacture.

	The push-to-pulse dials are also based on ICs. They usually
have a strapping option for make/break ratio and most will do a "Last
Number Redial". This is usually done by pushing the * key which of
course represents nothing in the pulse world. The push-to-pulse dial
as I recall came into use in the early eighties, twenty years after
touch-tone.

	Push-to-pulse has caused much confusion, with people thinking
it is touch tone etc. Only a cynic would say that it was intended to
confuse. One of the reasons that all the junk far east phones were
push-to-pulse was that is what they understood and could test on their
phone lines. It is actually cheaper to make an IC touch-tone dial than
a push-to-pulse jobbie.

> Sun Microsystems UK, Gatwick Office
                       ^^^^^^^^^^^^^^
	When I lived a few miles from here (Leigh) we had a manual
exchange as did Redhill, the big town up the road. This was in the
early sixties when they had touch-tone in the U.S.


Julian Macassey, n6are  julian@bongo.info.com  ucla-an!denwa!bongo!julian
N6ARE@K6IYK (Packet Radio) n6are.ampr.org [44.16.0.81] voice (213) 653-4495