PSTN Services Migration to IMS - Are SPs finally reaching the tipping point for large scale migrations?

Over the past decade, wireline Service Providers (SP) have been looking for ways to cost-effectively evolve the existing PSTN network to Next Generation Network (NGN). Many factors ranging from new technology immaturity, costs of migration, complexity of integration, to industry consolidation have impeded the decision making process to migrate the PSTN network to NGN. Underpinning these considerations is the industry's inability to identify and develop a clear set of new applications that could justify the investments and expenses required to migrate to the new environment with a positive Return On Investment (ROI). Recent efforts [1], [2], however, in the Telecommunication and Internet converged Services and Protocols for Advanced Networking (TISPAN) standards body have adapted the IP Multimedia Services (IMS) framework defined by the Third Generation Partnership Project (3GPP) [3] to wireline SP's applications and services. As a result, IMS has finally emerged as the prevalent consensus in the telecom industry for a target NGN that supports, among other capabilities, PSTN emulated/simulated voice services and multimedia applications. This paper examines the SP's needs, the services architectures and platforms, and the access technology alternatives for migrating the PSTN network to IMS. It further leverages experiences from recent engagements with SPs globally to propose solutions that will help accelerate the migration of PSTN services to IMS. Finally, it concludes that maintaining the status quo has increasingly become cost-prohibitive for SPs, and that the industry has reached the tipping point for large scale migrations of the existing PSTN services to IMS.