Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!att!pacbell.com!lll-winken!telecom-request From: 0004133373@mcimail.com (Donald E. Kimberlin) Newsgroups: comp.dcom.telecom Subject: Re: More on Frequency-Selective Ringing Message-ID: Date: 27 Mar 91 12:29:00 GMT Sender: Telecom@eecs.nwu.edu Organization: TELECOM Digest Lines: 58 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 247, Message 1 of 6 David Lesher carries on a thread that's been of interest to me for some decades now..that of just *who* used *what* selective ringing methods on multiparty lines. At the time and place of my arrival into the wonderment of "the phone company's way," all the methods he laid out for us were well-established. But, if you asked anyone reachable the why, who and wherefore, any answer you got was that *theirs* was the "standard way." (Sound like today, datacomm sports fans?) The best I've ever been able to sort out was that Bell had apparently developed along a line using 'divided ringing') (that is, ringing from one wire or the other to ground) for two-party or "super- imposed ringing" (adding polarity-sensing to the divided ringing) for four parties on one line. And, the Bell numbering scheme identifying these never got, to my knowledge beyond four different letters. All these range with 20 Hertz. Meantime, non-Bell telcos seemed to adopt W. W. Dean's frequency-selective ringing, and did so in the several variations -- Harmonic, Decimonic or Synchromonic -- and even some combinations of these in cases I observed, to make their basic complement more than the four or five the basic complements listed. (Here, I can add for David's interest that in the plant of GTE of Florida, the basic set seemed to be the "harmonic" set, but had 54 Hertz instead of 50, as well as 20 Hertz instead of 25 ... just to show how confusing it was. Perhaps this was an answer to the "falsing" suspicions David has. Needless, to say, you could often hear your ringer click or buzz when another party's frequency sailed down the line, anyway! GTE Florida's heritage came from having once been the Peninsular Telephone Company of Florida, which bragged it had "the first" Strowger-supplied automatic exchange, located in St. Petersburg. That may have been "the first" *they* knew about. But, its frequency- selective ringing may have started the plan in that company. And, those Strowger switches in their oak-framed glass cases were still ka-chunking away into the early 1960's!) Unanswered to my satisfaction is that Bell employees many times over the years told me that "Bell companies had 8-party service, too," but they were always evasive about *how* 8 parties could be rung with only 20 Hertz. And, I personally did some work replacing WECo 350/355 CDO's in rural Mississippi last year, to hear these stories proliferated. Yet, the old CDO's there had no evidence of ever having had anything but 20 Hertz ringing generators. So, my question to this forum, where someone certainly knows, is *how* did Bell accomplish 8- party ringing if they used only one frequency? Or, is it one of those bits of lore that had some truth someplace where perhaps Bell had acquired an Independent using frequency-selective ringing ... and then got the story embellished with retelling and retelling? So far, I never met anyone who could tell me just *how* Bell did eight-party with WECo-built appratus. (No weasel stories now, about apparatus WECo bought, resold and installed in some places. I know they'd do that if they had to!)