Patent ID: 7894593

Claim:
A method to select a numbering plan comprising: selecting, at a call state controller, a numbering plan from a plurality of numbering plans, wherein the numbering plan is selected to correspond to a calling party and at least one of a country of the calling party and a network of the calling party, wherein the calling party is in a home network which is a visited network where a called party is roaming; and converting a telephone number of the calling party in a format comprising a national format of said telephone number according to the at least one of the country or the network to another format comprising an international telephone number format of said telephone number using the numbering plan, the converted international telephone number of the calling party provided to an E.164 number translator to determine a session initiation protocol uniform resource identifier to enable a call back from the called party to the calling party, wherein said selecting and said converting are performed on least at one of a user equipment of the called party and a call state control function.