The 4712 Modification supercedes the 4711. It allows the user to have up to five ESN/NAM pairs available at one time. One use is to replace multiple phones, i.e. bill work calls to employer-provided phone, personal calls to personal phone. Or, one pair for the A carrier and one pair for the B carrier. For people who own the CTEK cable, a program is available to input all ESN/NAM info from the PC.