TELECOM Digest OnLine - Sorted: Re: Speed Dials

Re: Speed Dials

Tue, 12 Sep 2006 23:17:06 -0400

Mr Joseph Singer wrote:

> 11 Sep 2006 07:24:53 -0700 wrote:

>> The dial speed is about 10 pulses per second. (A good modem manual
>> will tell you exactly the "contact make/break" times and the settings
>> for outside the U.S. as well).

>> Anyway, I believe panel switching and certainly crossbar and ESS could
>> and would accept 20 pulses per second. Way back in HS a kid figured
>> out on his phone dial an adjustment to make it 20 p/s and it worked
>> (on either #1 xbar or panel). PBX switchboards had 20 p/s dials.

>> However, I think they realized this higher speed was rough on
>> equipment and did not provide it to the general public for that
>> reason.

> Personally, I don't believe it caused any more wear and tear on
> equipment than what a 10 pps dial would make on the system. Since
> panel, #1XB and #5XB all used common control and didn't do anything
> til the requisite amount of digits had been entered in the receiving
> registers likely could care less how fast the pulses came into the
> registers. And I don't think it caused any more wear and tear than
> receiving MF or DTMF.

> I don't know if SxS could handle it but SxS components had
> wear issues and certain improvements was rough on SxS unless it was
> carefully spread out among switches within an office.

> Wear issues weren't likely the problem with 20 pps dials o n SXS. The
> problem is that SXS systems cannot keep up with pulses as fast as 20
> pps. It might work *sometimes* but for constant reliable service 20
> pps dials would not likely have enough reliability to be used.

> As for "why subscribers were never given 20 pps dial phones as a usual
> thing" my guess is that WECO never put that into widespread production
> so it wasn't made available as a standard dial in a standard 302 or
> 500 (whichever would have been in use at the time.) When Touch-Tone
> (DTMF) came out in '64 it was a viable option that was going to
> eventually be implemented throughout the Bell System eventually.
> Whether this is the reason or not is only my speculation.

Until the 80s, phone gear was designed to last 30 or 40 years. That
faster pulsing could have eaten into THAT time frame on the phone set.
But I doubt it mattered much on the CO end.

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