Continuing our short series on the deployment status of IP Multimedia Subsystem (IMS) among carriers, today we'll hear from Alcatel-Lucent, one of the world's leading end-to-end IMS suppliers. We recently interviewed David Withington, marketing director for applications at Alcatel-Lucent. According to Withington, Alcatel-Lucent strongly believes that IMS is a great solution for consumer VoIP and that by first deploying an IMS-based VoIP architecture, carriers could then enable many other IMS compatible applications.

Once IMS is deployed for VoIP in the service providers’ infrastructure, carriers can then offer more personalized services followed by a move to IMS-based control of mobile services. Alcatel-Lucent is working to help mobile operators understand what is happening in residential VoIP so they can launch their own solutions bundled with their existing mobile offerings. Operators can also start immediately with new applications, using IMS enablers such presence, instant messaging and network address book to enrich their existing offerings.

When it comes to IMS control for enterprise services, Withington says that most large organizations still want a hybrid architecture that includes both hosted and premises-based VoIP and allow for both legacy (TDM) voice and IP-based voice to co-exist. Since few large enterprises want an immediate cut-over to a pure VoIP architecture, carriers are faced with managing interoperability between the legacy and next-generation IP deployments that can take years to evolve within the corporate network. Therefore, carriers must deploy both IMS (with corresponding SIP call-control features) and provide applications that span both legacy and IMS-based VoIP solutions. On the other hand, smaller enterprises can benefit immediately from a fully IMS-based approach according to Withington.

As for carrier-to-carrier IMS interoperability, Withington notes that most carriers still want to use traditional Signaling System 7 (SS7) interfaces for transfer points between carrier networks for many years, so IMS interoperability between carrier networks isn’t yet a “hard requirement.” Once carriers agree to make the transition from SS7 to IMS for carrier-to-carrier connections, Alcatel-Lucent will support that requirement.

Steve Taylor is president of Distributed Networking Associates and publisher/editor-in-chief of Webtorials. Larry Hettick is a principal analyst at Current Analysis.