I have a customer with a BCM 450. They have a toll free number that is pointed to one of their DID's. Every now and then, when someone dials that DID, the phone rings fast busy. If the customer reboots the system, it clears the problem. They've had to do this 3 times and it's worked all 3 times. This doesn't seem to be carrier and all the other DID's are ringing in fine.