Path: utzoo!telecom-request Date: 21 Jun 91 14:23:25 GMT From: Bryan Richardson Newsgroups: comp.dcom.telecom Subject: Re: What The Heck is "Fiber Optic Quality" Anyway? Reply-To: Bryan Richardson Message-ID: Organization: Department of Computer Science, Purdue University Sender: Telecom@eecs.nwu.edu Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 11, Issue 476, Message 1 of 8 Lines: 38 In article Jeff Carroll writes: > In article ivgate!macnet!jim.redelfs@ > uunet.uu.net writes: >> Mark Miller wrote: >>> as I understand it, virtually all long distance calls are sent in a >>> digital format. >> I believe this is in error. Although AT&T is actively replacing the >> analog facilities within their VAST system, I'm sure they have a LONG >> way to go. > This is certainly *not* the case in our corporate network, and > I'd guess that AT&T is still some time away from being fully digital, > as well. Every switch in the AT&T network is a digital switch with the exception of a single cross-bar (in North Dakota, I think), and perhaps a few TSPSs which haven't been replaced. If I remember correctly, the transmission facilities within the network are over 99% digital -- fiber, microwave, etc. Thus, it is highly likely that any call placed over the AT&T network is digital from the moment that it enters through the moment that it leaves the network. What often affects sound quality on a call (in addition to the Sports Illustrated phone), is the copper loop from the subscriber to the CO (always analog), the local CO, and the transmission medium from the CO to the AT&T network. Bryan Richardson richard@cs.purdue.edu AT&T Bell Laboratories and, for 1991, Purdue University Disclaimer: Neither AT&T nor Purdue are responsible for my opinions.