larry@uunet.uu.net (Larry Lippman) (05/21/91)
In article <telecom11.351.10@eecs.nwu.edu> roy@alanine.phri.nyu.edu (Roy Smith) writes: > Yesterday I found a fragment of a letterhead or invoice blank > from a business my grandfather owned once. The telephone number is > listed as "9305-R" (I'm not sure of the digits, but the -R is right). > I assume the -R means it's the ring side of a party line, but > it seems odd to me that a business would list that as part of their > phone number (this was a small business, just my grandfather with a > truck he owned, maybe one other partner, and it's likely it was his > home phone number). Didn't each party on a party line get assigned a > different last digit? If not, how does one dial a phone number like > "9305-R"; do you have to ask the operator to connect you? I suppose > it's likely that at this time, all calls were completed manually, so > that may not have been anything out of the ordinary. Actually, the four-party code identifier letters W, J, R and M have no known mnemonic significance. Their definition as applied to the Bell System superimposed selective ringing system are as follows: "W" = ring lead to ground, negative superimposed battery "J" = tip lead to ground, negative superimposed battery "R" = ring lead to ground, positive superimposed battery "M" = tip lead to ground, positive superimposed battery The party code identifier originated in manual telephone central office days when the call was completed solely by human operators. The above letters continued into automatic switching telephony as a convenient means of identifying the four possible fully-selective parties from an electrical standpoint; however, by the 1950's the "party code numbers" 1, 2, 3 and 4 pretty much replaced (respectively) the letters W, J, R and M. During the 1950's Bell Laboratories experimented with various electronic and quasi-electronic switching systems - including improved dialing methods - prior adoption of DTMF and the stored program control system later known as 1 ESS. During the course of such development, an unusual telephone set was developed with a dial that resembled the levers on a checkwriter. Each lever had ten positions (0 to 9) except for the right-most lever which had four positions labeled W, J, R and M for the party code identifier. The telephone worked by sending tone pulses using an electromechanical pulsing mechanism controlled by the levers. This particular telephone and associated switching apparatus was described and illustrated in the Bell System Technical Journal, circa 1954. For anyone who is interested, it is worth looking up the article because the picture of this telephone is priceless! Larry Lippman @ Recognition Research Corp. "Have you hugged your cat today?" VOICE: 716/688-1231 {boulder, rutgers, watmath}!ub!kitty!larry FAX: 716/741-9635 [note: ub=acsu.buffalo.edu] uunet!/ \aerion!larry