I am not sure what you mean by 'area code'? It is unusual for Freeview boxes to need any hint about their location because the antenna will be pointing to a local transmitter.
If it really is asking for an Area Code, that is the local telephonic prefix e.g. 01256.
Try a new question with more detail on the problem.
T
May 2009
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
