[Community] Modify the voice stream of a OpenPhoenux GTA04 mobile phone

Christoph Mair christoph.mair at gmail.com
Fri Aug 10 19:15:35 CEST 2012

Hi Jürgen,

On Fri, Aug 10, 2012 at 7:04 PM, Wurzer Juergen
<Juergen.Wurzer at fhstp.ac.at> wrote:
> Has a OpenPhoenux GTA04 mobile phone the possibility to modify/intercept the audio voice stream by an user space process
> for example to realize a answering machine or scramle the voice or hide a message by steganography into the voice
> or anything else.

> Would it be possible with a GTA04 mobile phone to intercept the audio voice stream of a gsm call and modify it?

Absolutely. It will however introduce some latencies because of a)
processing time and b) the longer way the audio data has to travel
from the microphone to the modem or from the modem to the speakers,
but it is possible. The GTA04A3 version needed a "sound-routing"
software to connect all things together. The GTA04A4 version also has
the possibility to let the soundcard hardware do the routing between
modem and mic/speakers. This lowers latencies and improves overall
audio quality, but if you want you can still use the "old" way and do
some processing in between.

Happy hacking!


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