Path: utzoo!mnetor!uunet!husc6!think!ames!ucbcad!ucbvax!JASPER.PALLADIAN.COM!dp From: dp@JASPER.PALLADIAN.COM (Jeffrey Del Papa) Newsgroups: comp.dcom.telecom Subject: Temporarily out of service Message-ID: <871203231158.1.DP@BANFF.PALLADIAN.COM> Date: 4 Dec 87 04:11:00 GMT References:Sender: usenet@ucbvax.BERKELEY.EDU Reply-To: Jeffrey Del Papa Organization: The ARPA Internet Lines: 22 Approved: telecom@xx.lcs.mit.edu 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.