What's the issue when all networks record for authorities, the encryption is thought to be broken and if they really want to get you spoof a mast.
Android apparently also allows a certain command set that allows the phone to be rung but not ring, pick up and listen, no display.. Although I'm not sure how that actually works but apparently it's possible. Via a certain CLI I wonder? Also if Webcams can be hacked by you and I relatively easily (it is) then I guess your camera could be compromised if there doors left open in the software...