A short Personal Identification Number (PIN) is used to transfer a subscription for wireless service to a new wireless terminal 104, thereby providing enhanced personal mobility to the subscriber. The transfer is rendered secure by the exchange of Diffie-Hellnan Encrypted Key Exchange (DH-EKE) messages...http://www.google.de/patents/US6260147?utm_source=gb-gplus-sharePatent US6260147 - Wireless subscription portability
