Hands free phone stopped working

Out of the blue today, my hands free phone won't work in my car stereo. The phone's Bluetooth menu shows that it's connected to the Kenwood, but the Kenwood won't read it. I tried reregistering the phone and it says that the device is full (I've only paired the one phone Env-2). When I try to delete the device to reregister, it shows no device to delete. I've had the stereo for months and it's worked great. Nothing happened, there were no changes to the car, the stereo or the phone. Today it just ceased to function properly. Help please.