Transformation of PSTN to Next Generation Network

Transformation of PSTN to NGN is a challenging goal for many legacy telecom operators. A smooth migration for PSTN will be an evolutionary process. It is expected that a new generation PSTN can extend the range of new services. Chunghwa Telecom is currently initiating an NGN_CN development which is part of NGN project for PSTN migration. In this paper, the key network technologies for PSTN migration are studied and NGN_CN network architecture is depicted. A three-stage PSTN migration process is proposed for legacy PSTN switch equipment replacement. The key routing issues for network migration are identified and a centralized routing architecture across service domains is proposed. An innovative service convergence architecture which integrates NGN_CN, Internet, and smart mobile devices is implemented for enhancing future PSTN services.