Path: utzoo!telecom-request Date: Thu, 6 Jun 1991 20:54:30 GMT From: Bud Couch Newsgroups: comp.dcom.telecom Subject: Re: Busying Out a Phone With a Resistor Message-ID: Organization: Kentrox Industries, Inc. 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 446, Message 6 of 7 Lines: 47 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 "accepted" way of busying out a line is to call your LEC and ask them to disconnect the service; they'll even stop charging you for it! Seriously, unless you have access to the CO switch internals, there is no clean way of busying a two-way loop-start subscriber line. _IF_ you have an incoming only line, what you have done should be kosher. With a two-way line, however, what you have done is to go off-hook, which the switch interprets as a request for service. When you do not provide any outgoing signaling, it will time out, and pull the cut-off relay, or the maintenence relay, or (in the case of old SXS) do nothing. Then the line just sits there, dissipating heat - in your resistor, the wires to you, and whatever relay or sensor is used in your serving CO. For a temporary thing this is not too bad, but it may also generated maintenence requests, etc, if left on for an extended period. If this line is a measured service line, you will be charged for all the time that you leave this on -- see my first paragraph. For what I perceive as a request for techno-weenie assistance: use your VOM as a milliammeter, and adjust the size of your resistor to pull 20 mA from the line. The rating (in watts) required will then be 0.0004 times the value of the resistor (in ohms). This is enough current to keep the line marked as off-hook, but minimizes the power wasted. Some of the newer CO's will show a pretty constant 30 mA for lower values of resistance. Keep raising the value until it goes down to 20 mA. Current lower than 20 mA may not work, so don't go lower. Bud Couch - ADC/Kentrox If my employer only knew... standard BS applies