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Cable Industry (Finally) Embraces SIP, Aligns With IMS Realm

News Analysis By Robert Liu
TMCnet Wireless and Technology Columnist


In my February News Analysis column, entitled Did Cable Miss the Boat with OCAP? I admittedly might have been a little overly harsh on the cable industry. In examining the OpenCable Application Platform (OCAP), I concluded that the cable industry might have been a bit short-sighted in adopting OCAP because voice signaling and QoS still relied on a separate platform.

Mea Culpa! In April, CableLabs, the industry R&D consortium, released its newest specifications outlining (finally) how to incorporate the now widely accepted Session Initiation Protocol (SIP) into clients through its PacketCable/DOCSIS interface standards for interoperability. The new specs also help align the cable industry with the IP Multimedia Subsystem (IMS) architecture that mobile operators, carriers, and service providers are using as the basis of their Next-Generation Networks (NGNs).

This is big news. Its not something we havent anticipated but its still big news because they are working to standardize on the Session Initiation Protocol, explained Gerry Kaufhold, principal analyst for In-Stats Converging Markets and Technologies Information Research Service.

Technically, CableLabs incorporated the Internet Engineering Task Forces (IETF) SIP into the PacketCable spec already with the release of version 1.5 back in 2004. But at that time, CableLabs engineers determined its Network-based Call Signaling (NCS) form of the Media Gateway Control Protocol (MGCP) served embedded clients better and only incorporated SIP at the backbone level to control signaling between softswitches.

That was a step toward the richer services that we always envisioned for the platform, said Ed Miller, Vice President of Advanced Network Systems at CableLabs. For the initial release, we decided to go forth with MGCP, which was more mature at the time.

The new specifications collectively known as PacketCable 2.0 define, in detail, the interface requirements needed for equipment manufacturers to develop interoperable products over the next few years. Now, in accordance with IMS specs found in 3GPP Release 5 and 6, if a user registers through a SIP client, for example, the SIP registration request is processed exactly how it would on a wireless network: authenticated through the Serving Call Server Control Function (S-CSCF) and linked in with the Home Subscriber Server (HSS) network elements.

Given that multi-service operators (MSOs) are in a heated race with regional Bell operating companies (RBOCs) to bundle services into a Quadruple Play offering, analysts believe the cable industry is shrewdly planning for the day when voice, video, and data can be integrated with wireless offerings.

The cable operators are not sitting still waiting for the Telco-TV guys to come in with a Quadruple Play that includes the cell phone as a delivery platform. Cable operators are moving proactively to make sure they can defend their incumbent position and, so far, they are doing pretty good, Kaufhold explained.

The In-Stat analyst may be right. At last check, only a small handful of neighborhoods are trialing the RBOCs IPTV offerings. Plus, as Cablevision implies from the repeated rhetoric of its key executives, cable MSOs arent likely to share their capacity-rich coax wiring that they own to the homes for RBOCs to complete the last mile of their Fiber-to-the-Neighborhood (FTTN) strategies.

With the RBOCs in less than one million homes marketing video and DSL rolled out to only 85 percent of their footprints, cable will continue to have the clear Triple Play advantage for some time, explained Doug Mitchelson, analyst at Deutsche Bank.

And Sprints much publicized joint venture with Comcast, Time Warner Cable, Cox and Advanced/Newhouse Communications isnt the only convergence game around anymore. Last month, NTL consolidated the U.K. cable market by merging with Telewest Global and then completed the last leg of a Quadruple Play when it reached an agreement to acquire Sir Richard Bransons Virgin Mobile Holdings.

So I think this new PacketCable specification certainly helps set the stage for the cable operators to expand as voice communications operators and also as mobile service operators, Kaufhold explained.

In the U.S. market, theyve looked more towards having an open standard so that all competitors can have a level playing field. So the PacketCable specification certainly opens up the possibility that a cable operator can become your complete telecommunications services provider... not just giving you voice, video, and data in your home. but following you and your communications needs throughout your day on your cell phone and other mobile devices that will emerge.

So, how much do existing independent software vendors (ISVs) need to customize their IMS wares to port applications onto the cable platform? Not much, if an application server was used as the development environment, but if an ISV is shopping around his/her wares as turnkey solutions, thats a different story, according to Eric Rosenfeld, Director of the PacketCable Architecture at CableLabs.

If youre looking at app servers, I think the idea was to minimize that. We wanted to allow the same applications to be plugged into the PacketCable platform. If you look at clients, its going to be a little bit more work, Rosenfeld told INTERNET TELEPHONY.

Thats because CableLabs engineers didnt stop with only the specifications outlined by 3GPP. It also added some semi-proprietary guidelines to manage elements that are inherent in the cable high-speed data network, such as Quality of Service, security configurations, provisioning, accounting and NAT/firewall traversal.

IMS only contemplates the cellular handset. Were looking for a much broader framework in which we can plug in different kinds of clients. IMS doesnt have a solution on how to traverse residential gateways, Rosenfeld explained.

Despite CableLabs enhancements though, officials claim that their goal was to still create an interface that allowed for an access-agnostic network.

I wouldnt say theres any one slant from any one vendor, the CableLabs official said. We didnt go off and do anything proprietary that favors one product over another. IT

Roberts 15-year communications career spans from the print world to television and to the Internet. He has covered business and technology writing for Dow Jones, Bloomberg Business News, CNN, and Jupitermedias He has served as a producer at CNN, Headline News and A&E Television Networks. You may contact Robert at [email protected].

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