How to Effectively Transition to VoIP and IMS

Big Bang or Phased Approach?
By Alcatel-Lucent
Posted July 2009

Abstract:

The IMS architecture provides a framework for developing large, converged service provider networks offering support of legacy fixed line and wireless access along with newer IP-based, 3G capabilities and blended services that span the different access devices. While not all service providers will benefit from the complex services portfolio IMS offers, many larger service providers are interested in evolving their networks to a full IMS architecture.

There are several approaches to moving a legacy network to full IMS architecture. A complete transition from a legacy TDM architecture is one option, which some service providers are selecting. For others, who have already implemented pre-IMS partial VoIP networks there may be the possibility of re-using the existing infrastructure to evolve to a full IMS network. Even for operators who have not yet ventured into IP voice networks it may be more effective to initially deploy a partial VoIP solution with a plan to evolve over time to full IMS.

For either of the partial VoIP paths there are several issues which most be addressed before proceeding. When starting with a earlier implementation of a partial VoIP network it is most important to evaluate the IMS readiness of equipment, infrastructure and operations processes. If planning a new partial VoIP network as a preliminary step to a full IMS transformation, it is important to work first through the details of the final IMS design so that the partial VoIP design can incorporate IMS network ready components and IT infrastructure that will facility re-use and ease of expansion during the transition to the final IMS network.