Path: utzoo!telecom-request Date: 5 Jun 91 17:48:25 GMT From: Toby Nixon Newsgroups: comp.dcom.telecom Subject: Re: Busying Out a Phone With a Resistor? Message-ID: Organization: Hayes Microcomputer Products, Norcross, GA Sender: Telecom@eecs.nwu.edu 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 427, Message 9 of 9 Lines: 36 In article , Marc Unangst writes: > I recently had one modem in the middle of a 15-line hunt group go out. > Not wanting to move the rest of the modems up a line each, I did some > investigation with a VOM and a telephone, and discovered that plugging > a 270 ohm resistor into the phone line (across tip and ring) should > have almost the exact same effect as an off-hook telephone does -- > thus busying out the line. Now, my question is, is there anything > wrong with doing something like this? Will a 1/2W resistor be enough? > Is this an "accepted" way of busying out a phone line? The FCC has said that it will no longer allow Part 68 registration of modems that busy out the line in this manner (i.e., by just going "off-hook"). Centrex is supposed to have a way to tell the CO that a particular line in a hunt group is unavailable. Bellcore is working on a DTMF signal that can be sent on the line to tell the switch that the circuit is busied-out (like the "Do Not Disturb" function on many PBXes). And FCC already specifies an RJ4MB data jack, in which, if you close the MB/MBC pair, notifies the switch that the circuit is busied-out. Nobody likes the RJ4MB solution, though, because it takes up an extra pair of wires for every circuit. The DTMF solution is what everybody is looking for. In the meantime, about the only way you can do it is by going "off-hook". Not being a hardware engineer, I can't comment on whether the resistor value you've chosen is appropriate for this function. I assume some of the telco experts here will comment for you. Toby Nixon, Principal Engineer | Voice +1-404-840-9200 Telex 151243420 Hayes Microcomputer Products Inc. | Fax +1-404-447-0178 CIS 70271,404 P.O. Box 105203 | UUCP uunet!hayes!tnixon AT&T !tnixon Atlanta, Georgia 30348 USA | Internet hayes!tnixon@uunet.uu.net