smb@ULYSSES.BTL.CSNET (11/11/85)
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.telecom@ucbvax.UUCP (11/27/85)
> 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. Well, I live in Durham now and I enjoy very much counting the clicks while waiting for the conversion to catch up with my tone dialing. If you listen carefully, you can still tell if you dialed the number correctly by how many clicks you hear.