Not quite two weeks ago a new channel type was added to asterisk-addons. This new channel is called chan_mobile. It allows a user to connect their Bluetooth enabled cellphone or headset to Asterisk. When a cellphone is connected to Asterisk, Asterisk will then handle incoming calls and can also use the cellphone to make outgoing calls. When a headset is connected, Asterisk can send calls to it and possibly originate calls.
I personally find this to be very cool. I just ordered a Bluetooth USB device so that I can try this out for myself. I’ll report back with the results in the near future, hopefully.