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Path: utzoo!watmath!clyde!cbosgd!ihnp4!ucbvax!telecom
From: prindle@NADC.ARPA
Newsgroups: mod.telecom
Subject: re: Alternate carrier access through CENTREX
Message-ID: <8601181847.AA09471@ucbvax.berkeley.edu>
Date: Thu, 16-Jan-86 08:16:21 EST
Article-I.D.: ucbvax.8601181847.AA09471
Posted: Thu Jan 16 08:16:21 1986
Date-Received: Sun, 19-Jan-86 05:29:23 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 5
Approved: telecom@mit-xx.arpa

You can determine which carrier you actually get by dialing
10xxx-1-700-555-4141 and listening to the recording you get.  This may
not be foolproof, as the CENTREX may handle the 700 differently than
calls to D.C. from Philadelphia, but, more likely, it just gives up
trying to route the call when it gets the 10xxx.