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From: omahony@swift.cs.tcd.ie
Newsgroups: comp.dcom.modems
Subject: Re: Cellular phones and modems
Message-ID: <1991May15.173017.7923@swift.cs.tcd.ie>
Date: 15 May 91 17:30:17 GMT
Article-I.D.: swift.1991May15.173017.7923
References: <0JPu22w163w@isishq.fidonet.org>
Organization: Computer Science Department, Trinity College Dublin
Lines: 33

In article <0JPu22w163w@isishq.fidonet.org>, evanc@isishq.fidonet.org (Evan Champion) writes:
> I was curious to know if it is possible to set up a modem on a cellular 
> phone (in the same fashion as a normal phone line).  Would I need any 
> special cabling, etc.?  Thanks.

A study was done by the Irish PTT on it's Cellphone network to determine how
good the network  was for carrying data.  Among their findings were the
following:

1. They needed an adaptor to go from a two-wire PSTN modem to the essentially
   four-wire operation of the cellphone's transceiver

2. V.32 operation at 9600 and 4800 proved impossible - in 95% of tests, the
   modems failed to negotiate

3. V22bis (2400) was better, but could not sustain a reliable service

4. V.22 (1200 bps) with MNP4 and MNP5 proved satisfactory with average
   throughputs of 945bps to 1442bps respectively.  These were approx
   60-65% of PSTN throughputs.

5. All the above tests were for stationary operation.  When the tests 
   were carried out on the move, the throughputs went down to 51% of
   normal PSTN throughput.


Although this is specific to the Irish CellNet, it may be of general interest.

Donal O'Mahony   omahony@cs.tcd.ie
Computer Science Dept
Trinity College
Dublin 2
Ireland