My new phone won't register to the base. It is the 7th phone i'm trying to register. This model only allows 6 phones but I only have 5 phones in use -I've had 2 phones damaged in the past. When i try to register the phone it says searching for base and then goes blank and shows G24 code. Is the problem the 7th phone? If so, how do i unregister a phone especially when they are damaged and thrown away?