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IMS day has not yet dawned

Posted: 01 Nov 2006 ?? ?Print Version ?Bookmark and Share

Keywords:IMS? IP Multimedia Subsystem? 3GPP? VON Conference? VoIP?

Carriers are pinning their hopes of deploying voice, video and vision services across all fixed and mobile networks on the Internet Protocol-based IP Multimedia Subsystem (IMS). But while IMS promises to usher in the era of true network convergence, participants at last September's VON conference cautioned that its day has not yet dawned. Indeed, several executives warned that many service providers, particularly wireless operators, are skeptical of IMS, a group of standards developed by the 3G Partnership Program (3GPP).

IMS might be the most reasonable path to fixed-mobile convergence, said Acme Packet chief executive Andy Ory, but such convergence "right now can be interpreted as 'wireless envy.' The wireless operators do not feel the pressure to change." They may begin to once the first generation of viable dual-mode Wi-Fi/cellular phones arrives.

Yet wireless operators have little incentive to enable customers to move to IP networks such as in-building Wi-Fi nets, where services cannot be billed by the minute.

IMS builds upon the IP-based soft-switch developments that emerged in the 1990s as Signaling System 7 replacements. Original soft-switch concepts used the more complex Media Gateway Control Protocol for network mediation, but the 3GPP version of soft switching was based on SIP clients everywhere. Though it originated in the wireless community, IMS found more immediate acceptance from wireline providers, which had worked with soft-switch architectures for nearly a decade.

Speakers at the conference touted the extension of IMS to IPTV services. This strategy aligned with VON founder Jeff Pulver's own plans for the conference, since VoIP has reached a stage of near maturity. Gateway developers are realizing that effective provisioning of multiple IPTV channels requires real-time control of special protocols like the Internet Group Membership Protocol, but the ability to exchange and mediate IPTV services across networks is still in its infancy.

While content developers already foresee a variety of IP "clipcast" and pseudo-broadcast services to offer in unified networks, the last thing anyone should look for at this early stage is a killer app, said Sonus Networks Inc. CEO Hassan Ahmed. IMS topologies are just beginning to bring together wireless, voice, data and video networks, and only end users can determine what types of services will dominate the IMS networks of the future.

IMS melds wireless, phone and cable access worlds, but who will sign on?

"If you think back to the very early days of the Internet and Arpanet, we're at the moral equivalent of X.25 days in IMS services," said Ahmed. The reticence shown by some carriers is natural, given the way open interfaces among networks of different types will change financial models for all carriers, he said.

Few carriers are resisting the transition of transport to IP, said Craig Gosselin, chief marketing officer of NewStep Networks Inc., a Canadian developer of IMS applications. The problem lies in the ability to actively manage and bill traffic that crosses different types of networks. In NewStep's evolutionary ladder, dual-mode services like cellular/Wi-Fi constitute the most difficult "total mobility" step for IMS. Before dual-mode services can be supported, carriers must work through single-mode/single-number and single-mode/extended-office services, each with more complex models of call routing and service gateway functions.

"A software developer has to continue to add features to the single-mode, single-number IMS services, but help the carriers move up to dual-mode services," Gosselin said. "Some of the Wi-Fi and WiMAX models can be scary to a wireless operator who isn't ready for unified service."

This is the type of migration Sylantro Systems has addressed in its Synergy 4.1 virtual wireless PBX. The system already has demonstrated handoffs for cellular/Wi-Fi phones, and Sylantro is experimenting with similar concepts for a Pakistan WiMAX network in which an 802.16e infrastructure developed by Motorola is layered with IMS services developed by Sylantro.

IP Multimedia Subsystem stole the limelight at VON. Though it promises fixed-mobile network convergence, some carriers remain skeptical.

Airvana Inc., which last spring launched its Universal Access Gateway, announced a deal with Tatara Systems Inc. The two will develop Windows Mobile clients capable of accessing TDM, Wi-Fi, WiMAX and Bluetooth services.

All such work implies greater monitoring and control of IP flows, a boon to test equipment vendors. The latest concept to shake up the performance analysis community is "quality of experience (QoE)," which Gary McFarlane, director of communications business marketing at Tektronix Inc., said is more than a subjective term. Just as QoS refers to specific transport characteristics of the network, QoE refers to measurable aspects of how end users perceive the quality of unified services.

Even embedded testing at the chip level fits this mold. Legerity elected to work with Texas Instruments Inc. to enhance its own voice test suite, giving TI's Piqua quality-management tools a boost in the process. Legerity has agreed to integrate its VeriVoice test suite for its subscriber-line chipsets with the Piqua algorithms for measuring IP voice quality. David Boikess, VP of sales and marketing at Legerity, said that this and earlier deals now link Legerity with virtually every VoIP chipset player in the industry.

All software and hardware developers at VON were united in saying they needed to diversify into IPTV and wireless services, because venture capitalists have become allergic to the term "VoIP" since the less-than-stellar IPO of Vonage. Danny Briere, president of analyst firm TeleChoice, said one shouldn't feel too sorry about Wall Street's hammering of Vonage.

"This company could have taken an early-adopter model for advanced IP services and pulled in the geeks for new services like video," Briere said. "Instead, they went to the central office for a simple voice-only model, and their stock is at $7 as a result. Vonage has an abysmal business model, and I don't see how it can go anywhere."

- Loring Wirbel
EE Times




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