Path: utzoo!attcan!uunet!wuarchive!brutus.cs.uiuc.edu!lll-winken!netsys!vector!telecom-gateway From: covert@covert.enet.dec.com (John R. Covert 22-Aug-1989 1357) Newsgroups: comp.dcom.telecom Subject: Re: Unusual Warning Notice on Phones Message-ID: Date: 22 Aug 89 17:57:49 GMT Sender: news@vector.Dallas.TX.US Lines: 23 Approved: telecom-request@vector.dallas.tx.us X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@vector.dallas.tx.us X-TELECOM-Digest: volume 9, issue 320, message 5 of 10 >While moving offices recently, we noticed the following odd label on the >bottom of AT&T straight sets (normal single line phones): > > WARNING > > USE FOR BUSINESS SYSTEMS ONLY OR YOU > RISK AN ELECTRICAL SHORT CIRCUIT. They're not _quite_ normal single line phones. If you look at the number on the bottom, you'll see that it is 2500 DM rather than 2500 D. The "M" means that the yellow-black pair is connected to a switch inside the phone which closes when you pick up the phone. This would be connected to the "A" and "A1" leads of a key system to make the lights on a key telephone light and to make your phone interact properly with your secretary's hold circuit, if necessary. The reason for the warning is that in older residential installations, Y-BK carries power for dial lights. And, to make matters worse, one series of transformers used to power those lights could create a fire hazard when shorted. /john