Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request From: John Higdon Newsgroups: comp.dcom.telecom Subject: Re: What Would it Take For Modems to Recognize Call Waiting? Message-ID: <11471@accuvax.nwu.edu> Date: 29 Aug 90 10:57:34 GMT Sender: news@accuvax.nwu.edu Reply-To: John Higdon Organization: Green Hills and Cows Lines: 29 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 10, Issue 605, Message 9 of 10 Steck Thomas writes: > PAT - I beg to differ with you on this one. On the older switching > systems, this may have been true. However, on the new ATT 5ESS and > the Northern Telecom DMS-100, call waiting is not implemented as a > voltage changee - simply a tone introduced to the line. There is no > true interuption of the line and no 'switching' sounds (clicks, etc..) > like there used to be. But even on these digital switches, the talk path is interrupted for the duration of the "beep". In most cases, this is enough for a modem to consider that there has been carrier loss and to hang up. There may be no clicks, but there is definately interruption of the line. If you don't believe me, call someone on a 5ESS or DMS100 who has call waiting and have them hum into the line. Then call them on another phone and see if you don't hear the person disappear for a moment. But that's all quite moot. There are so many 1AESS switches that will be around for so long as to make it impossible to discount their presence in the telecom world. Even the ancient 1ESS "serving" my home phone is not scheduled for replacement. ("Hell, we wouldn't want to waste money replacing THAT -- it still completes calls sometimes, doesn't it?") John Higdon | P. O. Box 7648 | +1 408 723 1395 john@bovine.ati.com | San Jose, CA 95150 | M o o !