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From: dave@westmark.westmark.com (Dave Levenson)
Newsgroups: comp.dcom.telecom
Subject: Re: Interoffice Signalling
Message-ID: <15848@accuvax.nwu.edu>
Date: 7 Jan 91 13:02:35 GMT
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X-Telecom-Digest: Volume 11, Issue 13, Message 3 of 12


In article <15840@accuvax.nwu.edu>, bill@toto.info.com (Bill Cerny)
writes:

> In the local switching environment, if two end offices are connected
> by interoffice trunks, how many digits are passed between offices when
> completing an interoffice call?  (assumptions: electronic offices,
> inband signalling, same NPA, same telco)

Anywhere from four to ten digits are sent between central offices as
described.  In most cases, five digits are sent.  Because most central
offices serve more than one prefix, but seldom more than ten, it is
customary to send a single-digit prefix-index followed by the last
four-digits of the called number.

> Side trivia: were #5 crossbar offices capable of supporting DID?

Some #5 crossbar switches were, and indeed still are, capable of
providing DID service.  They generate dial-pulse signaling toward the
customer equipment, unlike some of the more recent switch designs
which can send DTMF over such trunks.


Dave Levenson		Internet: dave@westmark.com
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