Hi everyone, 
I ask all those who well know OpenBTS some questions: 

1) By OpenBTS when a phone connects to it, is used a type of encryption GSM standard? If yes, which of A5/1, A5/2 and A5/3? And is possible, configuring OpenBTS, choose which encryption must use the phone to connect? OpenBTS also performs frequency hopping or not? And this is configurable? 

2) Can you listen with OpenBTS a call that crosses it? Or, can you record the traffic in a file?

3) I guess not because it is outside the scope of the project, but OpenBTS can communicate with other BTS (or other OpenBTS) via radio link? 

4) I propose, finally, a question that I had done. was reading in the wiki that laptops apple produce excellent performance, while the virtual machines do not. I am using a virtualized with vmware fusion on ubuntu MacBookPro. Discouraged me this solution? Someone has never experienced? Or can I continue to work even if I can get small wrong?

I thank in advance all those who answer me, and I apologize if my English is not perfect.
Greetings to all
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Federico Battaglia