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From: goldstein@DEREP.DEC (Fred R. Goldstein)
Newsgroups: mod.telecom
Subject: Called number ID service
Message-ID: <8512171440.AA09774@decwrl.DEC.COM>
Date: Tue, 17-Dec-85 09:28:02 EST
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Posted: Tue Dec 17 09:28:02 1985
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I hate to disappoint all of you in telecomland who are so sure that
"called number identification service" is impossible or at least 
unavailable, but it's been in trial for some time low.  Called Number
ID is one of the elements to Local Area Signalling Services (LASS),
which is one of Bellcore's secret weapons to save Centrex, among other
things.  It's implemented on the 1AESS, and probably soon on 5ESS, if
not other COs. 

A subscriber must, of course, pay for the service -- geegaws like the
Telident box are bunko.  CNID service works by having a data link from
the CO to the customer site.  Phone numbers from distant exchanges
_within_the_same_LATA_ are also included.  No beam-me-up-Scotty
technology there, either.  The data is sent around using CCIS (Common
Channel Interoffice Signalling -- a specialized packet network for
telephone signalling).  It doesn't cross LATA boundaries yet, but
the world's telephone companies are developing a new CCIS called 
Signalling System #7 whose design is optimized for inter-carrier use.
(I've got the CCITT Red Book spec here; it's quite a complex set
of protocols.)   Part of the CCIS/SS7 message is Calling Number ID.

Even if the originating CO is a stepper, today's technology provides
CNID capabilities.  Most small COs send toll traffic using CAMA 
(Centralized Automatic Call Accounting), in which the calling number
is sent in-band to the toll office for billing.  With LASS, the
toll office sends this along.

Calling Number ID is one of the services which is standarized in ISDN,
which in turn relies on SS7 for interoffice signalling.  Obscene phone
callers should stay away from the Florida LATA where the trials are
going on, and with widespread ISDN trials by 1987, who knows?