Transmitting voice with Osmocom

Fabio Pietrosanti (naif) lists at
Thu Apr 28 12:51:00 UTC 2011

On 4/28/11 2:00 PM, Huseyin Turan wrote:
> Thank you very much.
> A firm  from Turkey called Aselsan succeeded  to make encrypted
> conversation over GSM. It transfers the voice data  (1.2 kbit/s ) with
> Synthetic
> Voice Modulator technology.

That's a very cool approach of using DoV modem.

We've been also discussing about the possibility to directly encipher
the AMR or GSM-EFR payload that's inside the GSM frame.

This approach WOULD NOT SURVIVE to any transcoding, that means that
calls between different GSM networks will probably not work, but MAYBE
within the same GSM network it could work.

And it would be EXTREMELY efficient.

Think about negotiating a GSM-EFR payload running at 12.2kbit and
putting inside that payload an AMR 4.75 compressed and then enciphered

If there's no transcoding on the GSM network side it would works in a
very cool way with almost no latency and immediate call setup (that are
the typical issues of GSM CSD and Mobile VoIP products that several list
subscriber developer for their companies).


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