Audi Concert stuck on phone

Sounds like the telephone mute is stuck on. When power is passed through the telephone mute wire, it cuts off all other audio and replaces it with the telephone audio. So if anyones done any dodgy wiring or its a retrofit or the wiring has been modified in any way then this could be why. If it hasnt then u've prob got a fault somewhere for it to keep doing this.
 
Whip the stereo out (check you have the code just in case) there is a 10 way connector on the back - the one nearest the middle - pin 1 on that is the phone mute.

BTW you didn't mention if you have a phone kit fitted......
 
pull the fuse and see if it resets
scan with vcds for fault codes
 
Sorry for the lack of info but I don't have a phone connected and have not had a retrofit or any work done to it, I've had it (the car) about 6 months now and this is the first time it's happening it started working again yesterday but the same problem happened today. I might have to try removing it and checking the wires but I'm weary of this as I'm not too good with DIY