Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request
From: Martin Grossman <grossman@bbn.com>
Newsgroups: comp.dcom.telecom
Subject: Help Needed Building Home Intercom
Message-ID: <10989@accuvax.nwu.edu>
Date: 16 Aug 90 03:46:43 GMT
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X-Telecom-Digest: Volume 10, Issue 576, Message 9 of 12


I would like to setup a mini phone service at my home connecting just
two  or three phones.  What do I need to buy (Radio Shack) to do this?


            --------                        --------
            |phone |------------------------|phone |
            |      |------------------------|      |
            --------                        --------
            |ringer|                        |ringer|
            --------                        --------

MISC INFO:

  1) There will be no connections to any regular telco phone lines.
  2) The little box's above marked ringer should be small and right next
     to the phone(s).  They should just have 1 button each and ring the
     other phone(s) when depressed.
  3) The box's marked phone should be any phone that can be hooked upto
     the standard (US) phone system.
  4) I understand just a little about how phones work...
     a) I think its 50-60VAC at 20-30HZ to ring a phone
     b) phone looks like inf resistance/reactance when on hook
     c) phone looks like approx 680 ohms when off hook
     d) there's a small DC voltage when off hook

  5) The dial (or push buttons) won't be used (ie just the ringer box)
  6) This will be used instead of multiple walky-talkies.

USE:

  1) One phone will be in the basment and the other 1 or two will be
     upstairs.  I want to be able to signal (via the ringer) and talk
     without running upstairs or shouting. Besides...its a great project.

QUESTIONS:

  1) how do I connect tip and ring from each phone
  2) what do I need between the phones to act as the phone co.
  3) what do I use for the ringer box
  4) what do I need to add if I want to hookup a third phone or fourth.
     PS in no way am I trying to compete against MA-BELL.

Please send answers via email to: grossman@bbn.com