Asterisk & chan_mobile + raspberry pi + encryption GSM


I have an idea that I would like to present to anyone who can advise me if it is a good one or a bad one. I want to develop an asterisk module that will encrypt the voice data that comes through a sip channel and forward it to a Bluetooth connected device. I understood that asterisk + chan_mobile will do the trick for some mobile phones. I need some pointers of how can I do this or why I can’t do this. Basically, I am trying to simulate a “vpn” connection through asterisk over GSM( 3G, etc. won’t do ). Asterisk PBX will run on a raspberry pi with connection to the Bluetooth device and an ad-hoc network. The client(s) will connect through wireless. At the other end there will be a similar device.

  1. SIP Phone ----> Asterisk(raspberry + chan_mobile ) -->cell phone ------GSM------ ( first endpoint )
  2. -----GSM------cell phone------>Asterisk(raspberry + chan_mobile )--------> SIP Phone( second endpoint)

Waiting for any advice.

Does anybody know to whom might I address this question in order to get a small hint ?( or on which forum ) . Thanks.