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From: du4@mace.cc.purdue.edu (Ted Goldstein)
Newsgroups: comp.dcom.telecom
Subject: Building an Acoustic Coupler
Message-ID: <14218@accuvax.nwu.edu>
Date: 31 Oct 90 19:03:38 GMT
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X-Telecom-Digest: Volume 10, Issue 780, Message 3 of 13


Hello all,

     I am trying to build an external acoustic coupler for a direct
connect modem so it can be used with a foriegn phone system and I need
some phone gurus to tell me if my idea is possible or not.  Basically
my setup is as follows:
                                      _____ _____
                                      |   | |   |----------\ To phone line
                                      | __| |__ |----------/
                                      | |     | |
 ________      ________               | |     | |
 |      |      |      |               | |__ __| |
 | PC   | - - -|Modem |---------------|   | |   |
 |      |      |      |----   --------| A | | B |
 --------      --------   |   |       ----- -----
                           +9V        Two phones taped
                                      mic to speaker.

The idea is that the tones the modem puts out are converted to
acoustic by american phone 'A' and then converted back into phone line
signals by foriegn phone 'B'. The end goal is to use an American modem
in France.

I have tried this setup, and the modem does hear the dial tone, and
will attempt dialling, but can't hear the carrier from the answering
modem.

I am using el'cheapo (tm) phones for my tests, maybe they are
distorting the tones(?). Before I try again with better phones, I was
wondering if my theory is sound (no pun intended). Should this work?

I have also heard such a commercial device exists to accomplish this
task.  Any leads on this would also be welcome.

Any information, thoughts, ideas or product leads would be greatly
appreciated!


Ted Goldstein                            E-mail: du4@mace.cc.purdue.edu
Network and Systems Admninistrator       Phone : (317) 494-9070
Purdue University School of Technology   Office: Knoy Hall, Rm G009