Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request From: mitel!spock!grayt@uunet.uu.net (Tom Gray) Newsgroups: comp.dcom.telecom Subject: Re: Leaving Brief Messages With Free Collect Calls Message-ID: <12049@accuvax.nwu.edu> Date: 12 Sep 90 13:30:17 GMT Sender: news@accuvax.nwu.edu Reply-To: Tom Gray Organization: Mitel. Kanata (Ontario). Canada. Lines: 30 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 638, Message 2 of 13 In article <12000@accuvax.nwu.edu> ben@hpcvlx.cv.hp.com (Benjamin Ellsworth) writes: X-Telecom-Digest: Volume 10, Issue 635, Message 5 of 13 >> I have had occasions where people who called me have asked me, >> surprised, "How come you answered even before the phone rang at all?" >> when I had distinctly heard the phone ring twice at my end. >> Any switch gurus care to shed any light on this? >I am not a switch guru, but a professor of mine (Dr. Burton at BYU) >was an ex-Bell Labs man, and he mentioned in passing that some work >had gone into the long distance switching network to temporally >displace the ring that the caller heard from the ring signal that the >callee heard. This was done specifically to disrupt the "if it rings >twice, call me" type of signalling. Switch design spec's include requirements for immediate rng - both ringing current and audible ringing tone. However under conditions of high traffic it may not be possible to immediately give one or the other of these signals to the subscribers. Hence the possibility described above of a call being answered before rnging current or audible ringing is given. I have seen no spec's that require an offset of the signals as described above and I have read many switch spec's - and wiith practice I have even been able to translate some of these spec's into English. Indeed the spec with the best and most precise use of English came from the Mexican telephone company.