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.

http://www.aselsan.com.tr/images/dokuman/HC/AHSPD/kripto/2110/2110_whitepape...

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 payload.

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).

-naif