I have a customer that has had problems with caller id that clear up when the unit is power cycled - annoying but not the end of the world. Recently the unit started to hang up on callers before going through the programmed number of rings. This also cleared up after power cycling the unit but this is a bigger issue for the customer than the caller id problem. This unit has been in place about 4 years. Any ideas as to what might be going on and any things I can try to permanently fix the problems.