Data over normal GSM call

Andy Green andy at
Tue Apr 8 17:02:56 CEST 2008

Hash: SHA1

Somebody in the thread at some point said:
| 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.

I think you're right, but just a thought if you could issue ready-coded
GSM codec frames, you can put the data direct in there for >1KBytes/sec
or so.  It still has GSM frame format just not GSM data really in the
payload.  Of course what is on the other end has to realize you played
that game or it will sound very strange.

- -Andy

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