Data over normal GSM call

Mikko Rauhala mjrauhal at
Tue Apr 8 16:43:05 CEST 2008

On ti, 2008-04-08 at 10:22 -0400, Dan Staley wrote:
> I have plenty of cell minutes (not to mention free calls between certain
> numbers...) but I dont want to pay for a data I figure if I
> wanted to, I could just have my phone call my computer and transfer data
> over the line.

There has been talk of it (especially in connection to encrypted
phonecalls). The archives have a lot of it.

To summarize, you can't transfer very useful amounts of data over a GSM
voice call since we can't bypass the GSM chip's audio codec for those.
Obviously you can get some data through, but the highest anyone's gone
was IIRC ~1k using some kind of funky phonetic coding, but I believe
there was no exact reference to this either, let alone code (which would
be rather complex).

You could perhaps do stuff like update GPS coordinates through DTMF or
something like that, but for larger data transfer needs you really want
a data plan.

Mikko Rauhala <mjrauhal at>
University of Helsinki

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