Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request
From: jbayer@ispi.com (Jonathan Bayer)
Newsgroups: comp.dcom.telecom
Subject: Re: Modems and Phone Rates
Message-ID: <1798@accuvax.nwu.edu>
Date: 4 Dec 89 17:06:00 GMT
Sender: news@accuvax.nwu.edu
Organization: Intelligent Software Products, Inc.
Lines: 27
Approved: Telecom@eecs.nwu.edu
X-Submissions-To: telecom@eecs.nwu.edu
X-Administrivia-To: telecom-request@eecs.nwu.edu
X-Telecom-Digest: Volume 9, Issue 551, message 1 of 11

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.

Sorry, you're wrong.  The telephone network is designed to work with
human voices. As such the equipment multiplexes many conversations
onto a single wire.  Human conversation has many gaps that the network
can use to multiplex other conversations using the same frequency.  A
modem is on continously, tying up a frequency full-time.  Assuming
that a wire can handle 100 different conversations at one time, and
further assuming that 10 % of the conversations is quiet, that means
that with the proper equipment a single wire could handle 110
conversations at the same time. However, you use modems and all of a
sudden the network loses some of its excess capacity.

I am sure that my numbers are not correct, but the method is valid.  I
do not support the idea of extra charges for modem usage, and the
phone companies' numbers will have to be looked at very carefully,
however you cannot deny that modems _do_ take up bandwidth that
conversations do not.


Jonathan Bayer		Intelligent Software Products, Inc.
(201) 245-5922		500 Oakwood Ave.
jbayer@ispi.COM		Roselle Park, NJ   07204