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From: smb@ULYSSES.BTL.CSNET
Newsgroups: mod.telecom
Subject: Re:  TELECOM Digest V5 #64
Message-ID: <8511140513.AA13583@ucbvax.berkeley.edu>
Date: Mon, 11-Nov-85 11:01:09 EST
Article-I.D.: ucbvax.8511140513.AA13583
Posted: Mon Nov 11 11:01:09 1985
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	Date: Sat, 9 Nov 85 13:55:47 PST
	From: ihnp4!kitty!larry@ucbvax.berkeley.edu
	Subject: Re: Rochester telephone service
	
		Dialing speed (rotary (DP) or DTMF, no matter which) has absolutely NO
	effect on call completion success, the only exception being if your dialed
	digits are too slow or too fast for detection (i.e., < 6 || > 15 pps DP or
	> 10 digits/sec DTMF).  If you are in a crossbar office, you are effectively
	"offline" when dialing; your dialed digits are being decoded and stored in an
	`originating register' (OR).  Only when the OR detects the completion of a
	dialing sequence (or abort of same through a timeout) is the call routed to
	the `marker' for route section and transmission through the DDD network.

Umm -- that's not always the case.  When I lived in Durham, for example
(1972-1977), it most certainly was important.  (Durham is served by GTE.)  You
could hear the DTMF->pulse conversion going on as you dialed -- go too fast
and you'd confuse the switch.  This may, of course, have been an antiquted
switch; they didn't install automatic number identification equipment until
about 1974 or 1975, and then only under orders from the Utilities Commission.
Chapel Hill was even worse until Southern Bell bought the phone company from
the University (1978) and replaced the old step exchange with an ESS (1981).
One learned to listen to the click pattern as one dialed (rotary only, of course);
the wrong pattern of clicks meant you wouldn't get through.  (Have you ever tried
to exlain to a repair service clerk that you wanted to report a problem with
a bouncing relay on some trunk group, which you currently had seized, rather
than with some particular number?)  Once I was using an autodialer to call
the local Comp Center, on 933-9911.  The switch gave up after the first 3 or
4 digits and gave me a new dial tone in time for the fifth digit.  So I ended
up dialing 911...

		--Steve Bellovin
		AT&T Bell Laboratories

Anything I say here is my own opinions, not company policy, etc.