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The IP Multimedia Subsystem (News - Alert), better known as IMS, is nothing less than a vast new service architecture for the world’s wireless and wireline networks. Its humble beginnings were as a method for providing IP multimedia “Internet Services” over GPRS (General Packet Radio Service, the Mobile Data Service for users of GSM and IS-136 mobile phones) as formulated by the wireless standards body known as 3GPP (3rd Generation Partnership Project). A succession of other standards organization revised and expanded it beyond GPRS to include Wireless LANs, cdma200 and fixed-line communications, and to rely upon Internet protocols, particularly SIP (Session Initiation Protocol).

The primary benefit of IMS is that carriers and service providers can quickly and cost-effectively develop many voice and multimedia applications that will run in both wireline and mobile environments, thus achieving telecom’s long-awaited goal of true Fixed-Mobile Convergence (FMC).

Such a tremendous undertaking obviously requires new infrastructure elements, and all of these must be subject to rigorous interoperability testing. To facilitate these activities, the IMS Forum (www.imsforum.org) sprang up. Formerly known as the International Packet Communications Consortium (IPCC), today’s the IMS Forum is a global, non-profit industry association whose mission is to accelerate the interoperability of IMS applications and services for enterprise and residential consumers. To this end, the IMS Forum has created and organized a series of “IMS Plugfests”, the industry’s only event focused on IMS services interoperability verification and certification.

The first IMS Plugfest for Applications and Services was held January 15-19, 2007, at the University of New Hampshire’s InterOperability Lab (UNH-IOL) (www.iol.unh.edu) in Durham, New Hampshire, a renowned, vendor-neutral 32,000-square-foot testing center founded in 1988.

Plugfest I focused on basic voice, routing fundamentals and the interoperability of the IMS transport layer. Attendees included Ditech Networks, Empirix, Ixia (News - Alert), NE Technologies, Reef Point Systems, Sonus Networks, Starent Networks, Tekelec, Tektronix and Valid8.com, and was sponsored by Ditech, Empirix, GlobalTouch Telecom, Sonus Networks, Trendium and VoX Communications.

Manuel Vexler, chair of the IMS Forum Technical Working Groups, said, “IMS Plugfest I brought together IMS equipment vendors and service providers to establish agreed-upon requirements and criteria for IMS applications and services interoperability. One result was that the Forum was able to develop an industry-recognized ‘stamp of approval’ that could be used to expedite the rollout of IMS applications and services. Another result was that the participants demonstrated that service providers using IMS could bring a large best-of-breed central office switch up and running in just eight hours.”

Indeed. Fifteen carrier platforms were used to demonstrate a 250,000-subscriber network. Participants also demonstrated FMC services, PSTN Gateway and IP Centrex interoperability of their devices running in a multivendor IMS architecture.

“The first IMS plugfest validated the viability of a multivendor configuration, and we’ve built a reference test network that can be used to build things such as quad-play bundled services,” Vexler said.

And Plugfest I Begat Plugfest II
Plugfest II was held June 4-8, 2007, also at the UNH-IOL. Eighteen Forum member companies participated in Plugfest II, quickly deploying and debugging a complete end-to-end IMS network running IP Centrex, IM and rich multimedia applications. The results were first released at the IMS Forum’s members meeting at the Hyatt Regency in McCormick Place in Chicago on Monday, June 18, 2007, then made available in the IMS Forum’s booth at the neighboring NXTcomm (News - Alert) show held June 18-21. Visitors to the booth could speak with IMS Forum members who participated in the test event and view a video documentary of the Plugfest II testing produced by a Plugfest gold sponsor, Sonus Networks. The video was subsequently made available on YouTube.

Building on Plugfest I, the second Plugfest event tested interoperability for VoIP, IP Centrex, SMS (Short Messaging Service) and FMC functionality. IMS Services tested during Plugfest II included IM, voicemail, video sharing and advertising-supported free voice. The number of test cases in Plugfest II was increased from 13 (in Plugfest I) to 43.

“Plugfest II demonstrated that a service provider using IMS can start offering on-demand, IP multimedia and mobile services in just a few days,” Vexler said. “We’re now focusing on how applications and services interoperate in the network layer. For smaller vendors to challenge larger ones and show that they’re at the leading edge and can lead the market, they’ve to prove they have goods that are highly interoperable. Our Plugfests help them tremendously, because testing is far less expensive when you’ve got 15 or 20 vendors in a single lab with you. Plugfests particularly help when vendors start dealing with quadruple play bundles of services, since partnerships are necessary. They can adopt standard interfaces and not intimidate vendors with proprietary solutions, or else they have to keep things proprietary and not interoperate.”

Michael Khalilian, the IMS Forum’s Chairman and President, said, “Our second Plugfest was a great success and we are accelerating our testing timeline. Plugfest III will definitely be testing video and IPTV.”

Third Time a Charm?
The IMS Forum’s Plugfest III for Applications and Services will be held October 15-19, 2007, at the IMS Forum UNH Lab, Durham, New Hampshire. “This one will deal with more complex applications such as multimedia, IPTV (News - Alert), wireless functionality, security SIM card integration, IPsec and video conferencing. We may also debut the first gear to be certified by our forum,” Khalilian said. “Of course, we don’t actually certify individual network components. Instead, we certify component interoperability over particular applications. Each vendor’s gear is certified separately for SMS, multimedia, video conferencing, and so forth.”

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Richard Grigonis is editor of Internet Telephony (News - Alert) magazine. To see more of his articles, please visit his columnist page.