Same problem here. Spent countless hours using chat/phone/in-store and the closest I've come to any worthwhile information was from a tech who came to our house and said that in his 27 years of doing this, sometimes there is a clash on either the IP address or something related to the serial number or MAC. He said that the easiest solution is to change the device to any different device and the specific number you're having a problem with will go away. That's a bug in my book. Tried the suggestions here about Call Forwarding but didn't do me any good. Grrrrrrrr.
... View more