Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!wuarchive!zaphod.mps.ohio-state.edu!casbah.acns.nwu.edu!accuvax.nwu.edu!nucsrl!telecom-request From: john@bovine.ati.com (John Higdon) Newsgroups: comp.dcom.telecom Subject: Re: Interoffice Signalling Message-ID: <15847@accuvax.nwu.edu> Date: 7 Jan 91 11:00:42 GMT Sender: news@accuvax.nwu.edu Reply-To: John Higdon Organization: Green Hills and Cows Lines: 36 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 13, Message 2 of 12 bill@toto.info.com (Bill Cerny) writes: > In the local switching environment, if two end offices are connected > by interoffice trunks, how many digits are passed between offices when > completing an interoffice call? (assumptions: electronic offices, > inband signalling, same NPA, same telco) It varies, but usually works out like this: KP + Prefix code (one digit) + Number (four digits) + ST for a total of seven tones. Omission of the prefix code would be interpreted to mean the "0" prefix; possibly the first CG0 or MG0 prefix in the office. Since the stream is bracketed by KP/ST, variable length is easy. > Side trivia: were #5 crossbar offices capable of supporting DID? Absolutely. I remember many DID installations long before ESS had any significant penetration. The "CHUNK-KA-TUNK" when connected into the end office was unmistakable. Decades ago, the San Jose city offices used DID on a very crossbar switch. The first digital pagers were served via DID on crossbar here. There were some large Silly Valley firms who also made use of DID long before their COs were equipped with stored program equipment. Mind you, virtually all DID in those days was rotary signaling from the CO to the premise switch. In fact, when I put in an ITT 3100 for a customer that had DID service, Pac*Bell tried to talk me out of using DTMF. "Everyone uses rotary signaling." That was in 1984. Now DTMF is quite common. John Higdon | P. O. Box 7648 | +1 408 723 1395 john@bovine.ati.com | San Jose, CA 95150 | M o o !