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From: rkaufman@entec.Wichita.NCR.COM (Roger Kaufman)
Newsgroups: sci.electronics
Subject: Re: Phones used as intercoms
Summary: Radio Shack phone line intercoms
Message-ID: <759@entec.Wichita.NCR.COM>
Date: 20 Nov 90 16:34:31 GMT
References: <1990Nov12.181746.5465@syssoft.com> <1990Nov14.180524.3459@dlb.uucp>
Reply-To: rkaufman@entec.UUCP (Roger Kaufman)
Distribution: na
Organization: NCR Corporation, Wichita, KS
Lines: 46

In article <1990Nov14.180524.3459@dlb.uucp> dave@dlb.UUCP (Dave Buck) writes:
>In article <1990Nov12.181746.5465@syssoft.com> len@syssoft.com (Len Galasso) writes:
>>
>>I live in a four-bedroom, split-level house which has at least one phone
>>jack in each room.  What I'd like to do is to allow the phone "network"--
>>if you will--act like a local intercom when it isn't being used as a
>>regular phone system.

I live in a six-bedroom house spread over 4 levels :-) and so face the same
problem, but more so.  I have had good luck using intercoms bought at the
local Radio Shaft store.  They are the push-to-talk type with built-in 
speaker and mike, and plug into the phone jack.  The phone then plugs into
a jack on the intercom.  They use the two unused wires in the 4-wire phone
cable.  I think they put out an FM signal.  They also have a built-in hold
button to put the phone on hold.  I have found the advantages are:

   * No extra wiring.  They use the existing phone wiring system.

   * The signal doesn't go outside the house because the two unused wires
     of the phone cable don't connect to ma bell's system.

   * They are completely quiet when nobody's talking... no hiss.

   * Reasonably priced... about $50 a pair.

   * All work together like a big party line... each station talks to
     all others.  I now have 6 stations.

   * The hold button works great for putting a call on hold while you use
     the intercom to tell somebody two floors up that they have a call.
    
   * So far, no interference or stray pickup from any electronic source.

Disadvantages:

   * It does require an extra unit (in addition to the telephone) at every
     station location. 

   * With so many stations online, my system is starting to sound more
     like a pa system than an intercom. :-)

Anybody else had any experience with these?

-- 

Roger Kaufman, NCR PPD-Wichita, Wichita, Kansas, USA