Path: utzoo!mnetor!uunet!husc6!rutgers!ucla-cs!zen!ucbvax!mibte.UUCP!jbh From: jbh@mibte.UUCP (James Harvey) Newsgroups: comp.dcom.telecom Subject: Re: Temporarily out of service Message-ID: <2446@mibte.UUCP> Date: 21 Dec 87 18:18:53 GMT References: <871203231158.1.DP@BANFF.PALLADIAN.COM> Sender: daemon@ucbvax.BERKELEY.EDU Organization: Michigan Bell Telephone Company Lines: 48 Summary: just buy one Approved: telecom@xx.lcs.mit.edu In article <871203231158.1.DP@BANFF.PALLADIAN.COM>, dp@JASPER.PALLADIAN.COM (Jeffrey Del Papa) writes: > > Date: Tue, 24 Nov 87 09:02:34 EST > From: Phil Bowman > > > Does anyone out there know how to put a switch on a residential telco line > (the red and green wire) to simulate a busy condition to incoming callers > and to suppress the ring of the phone itself? Is there a way to add a > neon light to show the line is off-hook (I think there are 90 volts on the > line)? > > > ring prevention is fairly easy - a pair of diacs in series across the pair will > block ringing (a diac is a bistable 4 layer diode, below the threshold (40 volts > typically) it is an open circut, above it, a short.) > All subscriber loops have protective devices on them that shut down a voltage > source if a short is detected. thus ring (90v) is put on the loop, the diacs > conduct on the first half cycle, and the ring is removed from the loop. this > doesn't count as call completion, so the other party will often hear ringing > continue. diacs used to be available at rat shack, they may still be. > > Radio Schlock used to sell (think they still do) a device to suppress the ring. I think it's under ten bucks. It is popular with owners of the Commodore 1670 Modem which defaults to auto-answer every time you reset the computer. A resistor will busy out the phone but after a while the switching machine thinks there is trouble on the line and will disconnect it. It may be a while before you can get dial tone again after you remove the resistor. You might try simply ringing up some local recording and laying the receiver down on the table. -- Jim Harvey | "Ask not for whom the bell Michigan Bell Telephone | tolls and you will only pay 29777 Telegraph | Station-to-Station rates." Southfield, Mich. 48034 | ihnp4!mibte!jbh or try ulysses!gamma!mibte!jbh