TELECOM Digest OnLine - Sorted: Re: What Tandem in Telcom Means?

Re: What Tandem in Telcom Means?
Mon, 27 Dec 2004 09:13:24 EST

In a message dated Sat, 25 Dec 2004 00:53:57 -0800, writes:

> wrote:

>> In the late 1940s I made a call from a coin box in Los Angeles, and
>> the operator had to go to rate-and-route to learn which (manual) toll
>> tandem to plug into which had trunks toward the destination. L.A. had
>> so many outgoing manual toll trunks that they had to be distributed
>> among various tandems; as I recall, for my call the operator was
>> director to (manual) toll tandem No. 4. which had trunks for the MX
>> (multi-switch) routing to the destination.

> If you were calling out of the area before DDD came in effect in the
> late 1950s, there was always rate-and-route for calls out the LA area,
> and probably most areas of the country.

I'm not sure what point you are making. Toll operators had keyshelf
bulletins giving routes to the commonly called points, and in most
cases direct trunks to a large number of places directly in their

Rate-and-route operators existed everywhere, to determine the routing
to places with less traffic, including the smallest places and toll
stations, that were not listed on the keyshelf bulletin.

What I found unusual about Los Angeles was that it had outgoing trunks
to so many places that the toll operator had to know (whether from her
knowledge, the keyshelf bulletin or rate-and-route) not only that she
had to first reach a tandem with trunks to places not in her multiple
but that there were several different tandems because there were so
many different trunk groups they could not all be accomodated either
in the multiple before the operator or in a single toll tandem as was
the case in most places.

Wes Leatherock

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