How the Greek cellphone network was tapped.

[Eric Cronin]

On Jul 6, 2007, at 6:20 PM, John Ioannidis wrote:

>
> Unfortunately, it's not so easy to roll your own on top of a 3G- 
> enabled smartphone. The "broadband" channel does not have the tight  
> jitter and throughput guarantees that voice needs, and some  
> providers (Verizon in the USA for example) consider running voice  
> traffic over their "broadband" network a violation of the usage  
> agreement (no need to blame the government for that, their own  
> greed is adequate explanation). There are lots of other technical  
> and human-factors issues that have been covered to great extent in  
> this and other fora.
>
> /ji

The Cryptophone project in Europe <http://www.cryptophone.de/> has  
been trying to tackle the QoS issues for four or five years now.  I  
haven't looked at their implementation closely in several years, but  
back in 2002 or so they were using CSD (modem-modem calls) instead of  
the broadband channel, trading bandwidth for low jitter...  With  
current CPUs and audio codecs you can get decent voice quality over  
9600bps.

Thanks,
Eric
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