Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!bellcore!texbell!vector!telecom-gateway From: goldstein@delni.enet.dec.com Newsgroups: comp.dcom.telecom Subject: Re: ISDN Subscriber Equipment Message-ID:Date: 25 Sep 89 21:55:28 GMT Sender: news@vector.Dallas.TX.US Organization: Digital Equipment Corporation, Littleton MA USA Lines: 17 Approved: telecom-request@vector.dallas.tx.us X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@vector.dallas.tx.us X-TELECOM-Digest: volume 9, issue 411, message 3 of 8 In article , fff@mplex.UUCP (Fred Fierling) writes... >>From what I've read I understand that the U interface would be provided >via an single pair coming from the CO to the subscriber's premises and >terminate on an NT1 box which would provide the S/T interface to all >digital telephones on the premises. >Assuming this is correct, I understand that it would be possible for two >independent calls to be handled on each of the B channels. So, how would >both telephones perform call set up and tear down on the one D channel? The D channel has a contention-resolution protocol associated with it. Each terminal has a unique address (TEI) so the network knows which one is which; there's a procedure for auto-assigning TEIs, or they can be manually set. The TEI is part of the LAPD protocol, essentially a variant on LAPB with multiplexing. Fred