Earlier this year, we bemoaned the lack of proven multivendor interoperability as one of the roadblocks to a successful IP Multimedia Subsystem (IMS), as interoperability is needed to extend the usefulness of the IMS platform beyond voice applications. However, the IMS Forum hasn't been sitting by idly and last month at NXTcomm 08, they announced the interoperability results of NGN Plugfest 5.

In a prepared statement, Michael Khalilian, chairman and president of the IMS and NGN Forums said "We continue to evolve the Plugfests in response to emerging IMS technologies and industry advancements." He continued, "Plugfest 5 introduced interoperability and certification of the user-to-network 'Gm interface,' the vital link between end-users and service providers. We also took the service provider view on end-to-end applications and services deployment."

Plugfest 5 extended the success of previous interoperability events to test policy decision function, load balancing/sharing, user authorization credentials, service profiles creation, multimedia messaging and charging/billing.

Jeff Ogle, Senior Analyst, Carrier IP Telephony at Current Analysis considered the event to be a positive step “because as in the previous events it attempted to cover a specific and very critical area in addition to the typical interoperability and regression testing performed from the previous events,” according to his report on the topic.

However, Jeff also noted in his report that “the true effectiveness of the IMS/NGN Forum’s interoperability events will ultimately be judged by its ability to translate the work done into implementation agreements and ultimately standards. This is still an issue for the IMS/NGN Forum as it conspicuously lacks a significant number of large carriers and Tier 1 equipment makers in its membership.”

Jeff’s report on Plugfest 5 can be found here. To view our previous observations on IMS progress (including the mini-series we wrote on the topic at the beginning of the year) please click here and type “IMS” in the search window.

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