An apparatus and method for number portability for an IMS network. In one example the method may have the steps of: processing all calls with E.164 numbers in a BGCF (Breakout Gateway Control Function); executing digit analysis on a respective E.164 number in the BGCF; and querying, by the BGCF, a NPDB (portable number database) to retrieve a routing number if the respective E.164 number is ported.