Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!bionet!ames!attctc!vector!telecom-gateway From: vances@egvideo.uucp (Vance Shipley) Newsgroups: comp.dcom.telecom Subject: Re: While Phone Rings, Charges May Begin Message-ID: Date: 10 Jul 89 22:32:29 GMT Sender: news@vector.Dallas.TX.US Reply-To: vances@egvideo.UUCP (Vance Shipley) Organization: Linton Technology - SwitchView Lines: 21 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 232, message 8 of 12 In article lim@csvax.caltech.edu (Kian-Tat Lim) writes: > >The MCI spokesperson points out that this is *not* the same as lack of call >supervision, which caused "ring-no-answer" billing. > I believe that this sort of thing can happen because of transmission time for the supervisory signals. A user on one CO calls a distant CO; the supervisory signals to pass the destination and billing info are passed thru each switch along the path and then the end user terminal is rung. When the set is answered the CO sends the supervisory signals back to the originating CO along the same path they took to get there. Propagation delay is as much as 10 seconds I am told (this would not be typical). If the originator gave up before (real time) the destination answered the near CO would begin to send the necessary supervision signals toward the end CO. There is a window here where the path is reserved but no thru connection was ever achieved, this should not be billable. I should mention that with SS#7 (which MCI has in place) this should be changed for the better. Vance Shipley