A study on implementation issues of number portability in IMS networks

With the acceleration of network evolution to the packet-based all-IP network, a demand for the IMS which is defacto standard framework to provide IP services in the packet-based network, is increasing rapidly. Number Portability(NP) which has been contributing to facilitating of telephony company competition and increasing of user convenience in legacy circuit-based networks, is also becoming more challenging issue in IMS networks. However, there is no definitely specified solution to provide NP in the IMS standard. In this paper, we overview the general four NP schemes which have been used in the CS networks. Afterward, we discuss practical implementation issues to be considered when employ them into the IMS networks on the basis of the existing basic standards.