Data over normal GSM call

ramsesoriginal ramsesoriginal at
Thu Apr 10 22:55:17 CEST 2008

By applying some sort of modulation (fm? am? psm?) it should be
possible to transfere data over gsm, but on a much lower speed then
through the data channel.

On Thu, Apr 10, 2008 at 7:34 PM, Harald Welte <laforge at> wrote:
> On Tue, Apr 08, 2008 at 10:22:10AM -0400, Dan Staley wrote:
>  > Does anyone know if it is legal (in the standard TOS) with providers
>  > (such as ATnT) to send data over a normal phone call?
>  this is not possible, since regular voice calls for GSM are not
>  bit-transparent, i.e. the voice signal is coded and potentially re-coded
>  (transcoded) a number of time between the calling and receiving party.
>  Data calls over GSM are done using CSD.  They also use quite a lot more
>  error correction than voice calls.
>  --
>  - Harald Welte <laforge at>         
>  ============================================================================
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