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From: sgf@cs.brown.edu
Newsgroups: comp.dcom.telecom
Subject: Re: Modems and Phone Rates
Message-ID: <1855@accuvax.nwu.edu>
Date: 5 Dec 89 15:27:46 GMT
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X-Telecom-Digest: Volume 9, Issue 554, message 5 of 11


I tried to stay out of this, but...

david@elroy.jpl.nasa.gov (David Robinson) writes:

> From the discussion so far it appears that modems do not take up
>anymore phone network resources than a normal voice call, you get the
>same 4KHz bandwidth whether you are talking or using a modem.

jbayer@ispi.COM (Jonathan Bayer) writes:

>Sorry, you're wrong.  The telephone network is designed to work with
>human voices. As such the equipment multiplexes many conversations

Well, you're both half right. If your modem traffic is passing through
trunks (not just confined to two local loops served by the same end
office) you're going digital. A modem conversation is one continuous
scream and definitely (depending on how the signal is modulated/
compressed) takes up more trunk and switch bandwidth than the circuit
held by two people who have fallen asleep after phone sex.

If, however, your local loop (assumed still analog) is connected to
another local loop at the same end office via an analog switch, what
you've got is similar to an operator sitting in front of a patchboard
- an electrical circuit which doesn't care what it's carrying (you get
your 4KHz).

Then there's ISDN with digital local loops....


_/**/Sam_Fulcomer
sgf@cfm.brown.edu
sgf@browncs.bitnet