The SBCs are Coming!

According to a new report from market research firm Heavy Reading entitled "VOIP Session Border Controllers: A Heavy Reading Competitive Analysis," voice over IP softswitch vendors aren't yet giving the attention they should to session border controllers (SBCs)—largely because the solutions serve as an alternative to their current offerings. But carriers are increasingly issuing requests for proposal (RFPs) regarding SBCs, indicating that there is a growing interest in the technology.

Report author Graham Beniston explains that SBCs are essentially a more advanced version of a media gateway. Voice over IP, Beniston notes, doesn't stick to a simple port number for access, which creates a challenge when traversing firewalls. "There is a port number to listen to for, say, session initiation protocol," he says. "The trouble is that once that's started, the two endpoints then swap IP addresses and other port numbers at the application layer without telling the Layer 3 or Layer 4."

An older (and simpler) way of getting around this issue, Beniston says, is an application layer gateway—but SBCs add significant capabilities in terms of access control and network management, capabilities that differ with each solution. "The application layer gateway is quite a simple, stateless, dumb animal compared to the functionality in a normal session border controller," he says.

For smaller vendors like NexTone, Kagoor, Jasomi, and Tekelec, Beniston says, there's a significant opportunity to control the market before larger suppliers like Siemens, Nortel, or Lucent see the value in implementing the technology. "The major vendors have known about these issues, and they've mainly said, 'Well, we can handle these with gateways and extra software in the softswitch,'" he says.

Initially, the report suggests, larger vendors are likely to respond to carriers' requests for the technology by simply sourcing the products through partnerships with smaller vendors—though they may turn to acquisitions down the road in order to add SBC functionality to their portfolios. In those cases, acquiring the same smaller companies that they've been partnering with would be the most obvious way to proceed.

In evaluating various companies' SBC offerings, the report looks at 40 products from 23 manufacturers. "I used a variety of metrics, some quantitative and some not," Beniston says. "My key metric is a quantitative one, and that's the number of simultaneous sessions that can be handled per U of rack height of equipment."

In the future, Beniston says, SBCs will of course continue to evolve. Many companies are looking at a more distributed approach, separating various components of the system for increased efficiency—and SBCs are also being employed to bridge the gap or "translate" between different PBXs. "You get lots of mergers and acquisitions where you try to put the IT systems together, and one of them is using SIP and the other one's using H.323, and you've got lots of potential problems," he says. "So you just stick a new box in the middle—and do a magic conversion between the two."