Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!dsinc!casbah.acns.nwu.edu!nucsrl!telecom-request From: john@zygot.ati.com (John Higdon) Newsgroups: comp.dcom.telecom Subject: Re: Answer Supervision From Loop Start Circuits Message-ID: Date: 15 Feb 91 08:00:00 GMT Sender: news@casbah.acns.nwu.edu Reply-To: John Higdon Organization: Green Hills and Cows Lines: 28 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 117, Message 9 of 12 Dave Levenson writes: > What all of these switches do provide is an open circuit interval (500 > msec for ESS, ~100 msec for 5 crossbar) when the far end party > disconnects. This is not supervision. While very much a hack, it works like this: On a 1(A)ESS, if a line is furnished from a Centrex port, the three-way has a peculiar property. With the first call in progress, the Centrex party flashes the hook for a second dial tone. The call progresses and when it supervises there is an open loop signal AT THE MOMENT OF SUPERVISION. Actually, I find this most annoying. I add the second call to the connection and when it comes off hook, about 500 milliseconds later there is a big KA-PLUNK (the "supervision indication"). The problem with this hack is that you need a first call up before the trick works. In scummy Pac*Bell Land, that call must be supervised (or incoming) before you can even get three-way dial tone. So somebody somewhere has to be paying for that other call. It's a neat hack and it really does provide reliable supervision indication, but it is also a bit cumbersome. John Higdon | P. O. Box 7648 | +1 408 723 1395 john@zygot.ati.com | San Jose, CA 95150 | M o o !