Path: utzoo!utgpu!watserv1!watmath!att!bellcore!rutgers!usc!zaphod.mps.ohio-state.edu!van-bc!ubc-cs!uw-beaver!sumax!quick!dsinet!marka
From: marka@dsinet (elroy)
Newsgroups: comp.dcom.modems
Subject: Re: Phone line busy indicator
Summary: how about this...
Message-ID: <298@elroy>
Date: 10 Jul 90 20:28:55 GMT
References: <9006270705.AA09386@ucbvax.Berkeley.EDU>
Organization: Digital Systems Intl., Inc.
Lines: 17

In article <9006270705.AA09386@ucbvax.Berkeley.EDU>, JAJZ801@CALSTATE.BITNET (Jeff Sicherman,CSU Long Beach) writes:
> 
>   Does anyone know of a device, Radio Shack like or mail order,
> that can be attached to extension phones of a single-line home
> type system to indicate when the line is already in use, so that
> a handset is not picked-up while i'm on line with my modem.

The December 1989 issue of Popular Electronics has a simple circuit (a
triac, a diode, and a resistor) that will act as a cut-off device.  You
place one of thses devices on each phone line, and the first phone to get
picked up gets exclusive access to the line.  All the extensions are cut
off until the first phone is hung up.

It's simple, cheap, and doesn't require re-wiring the phones.
-- 
Mark Anacker				...!dsinet!marka -or- ...!toybox!msa
Digital Systems International, Inc.	Redmond, WA   USA    (206) 881-7544