IP Multimedia Subsystem protocol—IMS to its friends—seems to be settling into a level of sanity after a year of insane predictions that it would replace sliced bread as the eighth wonder of the world. Last week’s GlobalComm telecom gathering in Chicago should have been an IMS lovefest—and from the vendor perspective it was, to an extent—but during show panel sessions, calmer heads prevailed. As a primer, IMS is a protocol that is expected to key the convergence of fixed and mobile networks and make communications one big happy network. It was originally developed to help wireless carriers move multimedia content onto their third generation devices, but has since acquired an almost utopian aura as the protocol that will merge fixed and mobile networks. It’s believed that the first to get to fixed-mobile convergence (FMC) with or without IMS—mobile carriers, telcos or cable—will win the battle for the elusive quadruple play of fixed and mobile voice, video and high-speed data. The thing is, IMS, despite what vendors will generally tell you, has been more hype than substance. It’s a difficult protocol to place into existing networks; it’s tangled in conflicting standards bodies; and it really has no definition of what it’s expected to produce other than that it’s supposed to converge fixed and mobile networks. It’s the services, stupid While IMS “does a lot to achieve” the convergence of networks by providing a standard way of “generalized roaming,” it may be headed in the wrong technology direction, suggested Siroos Afshar, chief architect, VoIP Network, at AT&T, speaking at an International Engineering Consortium Executive Forum panel titled “Mobility and Wireline Convergence: Merger or Collision.” It “does not make sense to say the access technologies will converge,” said Afshar, taking aim at those who would blend wireless and wireline technologies. “What does converge is the service.” In Afshar’s view of the converged world, services such as voice and data and video all blend together into a stream that can be delivered to just a few devices either on the premises or outside in the wider wireless cloud. The transport mechanisms—mobile, wireline telco, cable, Wi-Fi, WiMAX or whatever else—stay the same. “Access technologies cannot converge because it does not make sense to converge them,” he said. “Services must converge.” The HSS theory That theory seems to coincide with technology that MetaSwitch is developing for the home subscriber server (HSS), an integral element of any converged offering. “This concept of breaking out the subscriber database as the separate entity in the network makes a lot of sense,” said Andy Randall, vice president of marketing at MetaSwitch. Since MetaSwitch was already moving its softswitch architecture in that direction, “why wouldn’t we use it more off-the-shelf with IMS?” Randall wondered. “To some extent, it’s a natural evolution.” Randall’s thoughts seemed to run parallel to Afshar’s when it came to how FMC will evolve—with or without IMS. “A lot of industry standards bodies are working on taking standards and giving direction,” said Randall, who called all this work “fragmentation. We’re in a situation of people buying what works, and if vendors can make technologies around IMS that work and solve real-world problems, then they’ll get deployed.” Multiplicity There is another little issue with IMS and converged applications: There is a plethora of devices set to receive the content and services, and that list of devices continues to grow unabated. The best part of convergence will be the ability to deliver multiple services over one network to one device. “Forget about the technology and the architecture,” said Afshar. “I want to be able to communicate with my device anywhere I go” and receive “the same service over any of these access technologies.” The point to embrace, he said, is that “we don’t have cellular services; we have services.” And that, said Martin Cooper, the panel’s chairman and executive chairman and co-founder of ArrayComm, is what IMS or any other so-called convergence technology should resolve. “The technology must be invisible to the people that use the services,” Martin said. “The issue is not convergence—it really is moving forward.” IMS could be the tool that moves things forward, said Randall. “Twelve months ago it seemed like it was all push from the vendors, but what we’ve seen over the last 12 months is the major carriers all getting on board with this,” he said. This includes cable, which was represented at the telecom show as well. “With the cable world, they’re doing some of the same things with standards in their PacketCable areas,” he said. – Jim Barthold

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