An Application Server Approach for Number Portability in IMS networks

Number portability (NP) is an important requirement present in most telephony networks. Typically, NP is regulated by local legislation and is inherently against the very nature of routing in circuit-switched networks, which can complicate its deployment. The technological move towards IP-based networks demands treatment of legacy numbers portability, so as to enable interoperability among technologies and allowing progressive substitution of old networks. This paper aims at presenting an application serverbased approach for NP aimed at NGN networks, especially IMS. A test implementation is presented, along with a discussion of currently used approaches, as well as of the one here proposed. Test results validate the approach and show good overall performance.