Caller ID is a subscription service. You must subscribe to this service from your telephone service provider for this feature to work on your phone. The caller may not be calling from an area that supports caller ID. Both your and your caller’s telephone service providers must use caller ID compatible equipment.
Make sure the answering system is on. ANS ON light on the telephone should be on. Make sure the memory of the answering system is not full. If there is a fax machine connected to the same telephone line, try disconnecting the fax machine. If that solves the problem, consult your fax machine documentation for information on compatibility with answering systems