Path: utzoo!telecom-request Date: 29 Apr 91 17:11:31 GMT From: Toby Nixon Newsgroups: comp.dcom.telecom Subject: Re: Help Needed Understanding ISDN Message-ID: Organization: Hayes Microcomputer Products, Norcross, GA 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 318, Message 6 of 11 Lines: 34 In article , ac220@cleveland.freenet.edu (Rich Szabo) writes: > I am sketchy on how ISDN interacts and co-exists with Plain Old > Telephone Service. Does an ISDN line have a "phone number?" If so, > what happens if I dial this number from a Plain Old Telephone? Can an > ISDN line be used as a voice line so that I don't need a POTS line in > addition? An ISDN Basic Rate Interface as two 64000bps bearer channels. Except for the analog local loops, POTS is based on exactly this same kind of channel! Once you get into the CO, you can connect a digitized 64kbps POTS PCM voice channel to an ISDN B channel, and talk just fine. You definitely don't need to keep a POTS line around once you have ISDN. Of course, there's a lot more you can do with that 64kbps channel in ISDN than in POTS -- clear channel 64kbps synchronous transfers, V.110 or V.120 terminal adaption, X.25, etc. When it's being used for 3.1KHz voice or voiceband data, the network knows this so that it can route you to POTS lines (it will reject attempts to connect those other call types to POTS lines). Also, if the network knows you're using the channel for voice or voiceband data, it knows it can do voice compression and multiplexing on the channel -- but this happens primarily on international calls (rarely on domestic calls). Don't tell the network you're using the circuit for voice and then use it for something else, because strange things will happen. Toby Nixon, Principal Engineer | Voice +1-404-840-9200 Telex 151243420 Hayes Microcomputer Products Inc. | Fax +1-404-447-0178 CIS 70271,404 P.O. Box 105203 | UUCP uunet!hayes!tnixon AT&T !tnixon Atlanta, Georgia 30348 USA | Internet hayes!tnixon@uunet.uu.net