Fixed it - "Is your Computer plugged in" - The IT Crowd
The switch on the top left SIDE is the mute switch. I had the same problem, missed a butt load of calls couldn't find the answer here (Probably because it was such a stupid question) OK, now I feel like an idiot.
Originally Posted by ecaramaschi
BTW, vibrate does not effect the ringing when the iphone is plugged in. At least not on mine. I tried it and the phone would still not ring.
Now all is fine and dandy. kinda like plugging in the toaster.