ENUM-based Number Portability for Mobile Communication Networks

Typically, people usually enjoy new services and lower service rates. However, while changing the mobile operators, the subscribers should change the original Mobile Station International Subscriber Directory Numbers (MSISDNs) and notify their friends the new MSISDNs. Due to the effort of changing the MSISDNs, the subscribers may give up using the new services and lower service rates. The Number Portability (NP) service enables the subscribers to keep their original MSISDNs while changing their mobile operators. Thus, the NP service is very important in 4G/5G mobile communications. To provide the NP service for 4G/5G, this paper proposes the call routing mechanisms and the enhancement based on E.164 NUmber Mapping (ENUM) and the IP Multimedia Subsystem (IMS) architecture.