Encrypted calls - Cryptophone.de protocol

Thomas Gstädtner thomas at gstaedtner.net
Sat Aug 23 17:56:42 CEST 2008

Mikko Rauhala schrieb:
> ed for security review purposes only.
> However, they do also state that they have no problem with somebody else
That is really interesting!
We discussed this topic several times, but I think so far nobody had the 
idea to use old fashioned CSD data calls.
I said myself it wouldn't be possible as getting encrypted data over GSM 
voice calls is pretty much impossible and over GPRS the latency makes 
calls useless, but this really seems to be a decent way.

Most GSM networks support 9.6k, some of the better networks 14.4k, what 
means even with some overhead it should be possible to get 6-12k speex 
over it, what should allow an acceptable voice quality.

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