For several years, some within cable’s technical community have been gnawing away at the industry’s seeming lackluster attitude toward session initiation protocol (SIP) and its place within cable’s voice strategy. While industry defenders will tell you that SIP always had a place in PacketCable, it certainly wasn’t being pursued with the vigor of cable’s wireline and wireless voice competition, which caused some dissension among the rank-and-file techno community-although you’d be hard pressed to ever hear anything said publicly. Now it doesn’t matter. CableLabs, which, when it comes down to it, is the cable industry’s technology arm, has issued a series of specifications that were developed in alignment with the Internet Protocol Multimedia Subsystem (IMS) architecture being developed by the Third Generation Partnership Project. The 3GPP, for those who don’t speak standards and wireless and telecom, is a collaboration agreement bringing together multiple telecommunications standards bodies to produce technical specifications and technical reports for a 3rd Generation Mobile System. IMS is a big piece of 3GPP, although there is argument over how much attention it’s getting, and IMS by definition includes SIP. It also includes fixed-mobile convergence (FMC) capabilities, and cable is serious about FMC, the fourth piece of its voice, video and data bundle-see Sprint-Nextel JV as a reference point. SIP and innovation “SIP is where an awful lot of innovation is occurring right now-the SIP-based protocol and the environment that it supports,” conceded Eric Rosenfeld, director of PacketCable architecture at CableLabs, who said the R&D organization started looking “very closely at what we can do with SIP in late 2004 and early 2005.” That “look” signaled a strategy shift from a SIP avoidance policy the industry tacitly adopted nine years ago when the protocol first reared up in the telecommunications space. “Based on the focus of the service (in 1996), the idea was to use something that’s more mature at the time to reach down to our end points,” said Rosenfeld. “SIP has always been a part of the PacketCable architecture that we use for the back end of communicating between various softswitches and interconnecting softswitches to PSTN gateways … but way back when, it wasn’t mature enough, and it didn’t support all the things that we needed in order to provide a telephony service.” Cable’s wireless play Way back when, in fact, cable operators were scurrying to free themselves of any mobile wireless entanglements. Today, they’re letting out rope to such activities as a joint venture with Sprint-Nextel and are seriously looking at SIP as an element of IMS that will, in its purest form, enable FMC. SIP is now “much more mature than it was nine years ago; nine years is a couple of lifetimes in this industry,” said Rosenfeld. True enough. In those lifetimes, cable abandoned wireless then came running back into the fold. SIP, meanwhile, continued to germinate, and IMS sprouted from its fertile ground. As that happened, the wireless industry grabbed onto IMS as a way to link its so-called broadband services to the wireline broadband services. That, for anyone paying attention, also raised the specter of a Verizon Wireless linking with a Verizon wireline or a Cingular joining up with its parents at AT&T and delivering a service that cable could not match, and that, of course, created Excedrin headache No. 42 for cable operators who had blithely abandoned their wireless plays and had to swallow a joint venture with Sprint. Goes both ways Rosenfeld, putting a good face on SIP and IMS, insisted that cable was always doing something with the protocol even when it wasn’t doing anything publicly. “Some of the things we actually use in our SIP specifications are now being leveraged by IMS,” Rosenfeld said. “They’ve actually used things that we specified many years ago … and now we’re using things that they’ve put all together. It’s been almost collaborative, even though not by original intention.” SIP will, he said, change the way cable looks at and delivers voice services. “We’ll be able to support all kinds of different and innovative clients that will be able to hook into the infrastructure using SIP,” he said. “You’ll see new kinds of things and operators over time augmenting their existing capabilities for telephony with new kinds of clients for new kinds of services or integrated services.” Voice foundation The thing that made it all happen was the cable industry’s successful launch of voice services using PacketCable-sans SIP or at least mostly sans SIP. “They’ve (MSOs) been wrapping up customers left and right … and we started to turn our attention to what we should do with the architecture next to complete the original vision of supporting a broad range of multimedia services,” he concluded. – Jim Barthold

The Daily


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With Comcast and DISH not carrying Denver Nuggets RSN Altitude Sports for more than two years, the market is a bit ahead of the times as MVPDs reckon with the regional sports model. That observation came from

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