larry@uunet.uu.net (Larry Lippman) (04/02/91)
In article <telecom11.252.7@eecs.nwu.edu> wb8foz@mthvax.cs.miami.edu (David Lesher) writes: > While I have not dug too deeply into this aspect, one advantage of at > least the two party Bell method was ANI. While the trick with the > tapped ringer coil added some noise, it DID allow the CO to figure if > Mr. Tip or Ms. Ring was calling Fargo without a "numberpleeze." > The isolators, such as a 28A or a 425A, are gas tubes. They don't > conduct until a LARGE (~90v) dc voltage is impressed on the line. > Ringing is on top of that. Thus, during talking, no unbalance thru the > ringer coil, and less noise. But, if you have a 28A or other of the > myriad items Ma mentions (11A's, 687B's, 425&6A tubes, 426N diodes and > D180036 isolators, to name a few) can you ALSO have ANI, and if so, > HOW? ANI party detection based upon a balanced ground was only used with two party lines which had fully selective ringing. Four party and eight party lines were always assigned a class of service for ONI if the originating CO were equipped with ANI. > Here's a mix of old and new: Can you have party line selective > ringing on ESS's? ESS always had the technical support for two party, four party and eight party lines. However, contemporary with new ESS installation was usually an effort to upgrade outside cable plant to minimize or even eliminate party lines. No operating telephone company really wants to maintain party lines. This was also accompanied by a tariff change filing and notification of affected party line subscribers that they *had* to change to private line service. In some cases where a state public utility commission would not permit total elimination of party line tariffs, the telephone company would bill a "recalcitrant" subscriber at a lower rate for two party service, but in fact give them the equivalent of a private line. To make this "legal" for accounting purposes, the subscriber in question was often assigned the "ring party" on a hypothetical two party line. For practical purposes, the ring party on a two party line is no different from that of a regular subscriber with a private line. 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