How to configure Caller ID settings on Panasonic DECT 6.0 phone

On a Panasonic DECT 6.0 Phone, when a call comes in, the caller ID comes up with 1 plus the area code. I would like to remove the 1 in the caller ID so that it will be easier to callback using the caller ID feature. Is there a way to do so? Or is there a way to callback using that format without getting an error?
