The population of cellular phone roamers has been increasing every year. Most of them may want to use their original phone numbers while others may want to use other phone numbers of visiting countries. We are interested in providing multiple phone numbers across heterogeneous networks, which will lead various business opportunities. Therefore, we present a software framework which will provide multiple MSISDN while using single IMSI. The update location procedure is modified to transfer user's additional MSISDN on an ISD message. Also, the mobile terminating call procedure is modified to indicate the dialled number to the receiver. In simulation, our scheme increases lesser traffic transmission cost than the standard scheme.