The session border controller is a network element that always seems to be in the thick of things. And it appears that it will maintain that position as the communications industry moves forward with important new technologies including network functions virtualization, software-defined networking, and WebRTC.

SBCs gained prominence as appliances providing security at service provider-to-service provider interconnection points, an important application for which these solutions are still used today. But in recent years several vendors have come out with software-only SBCs as an alternative to those specialized hardware/software solutions, and the applications for SBCs have expanded to address a wider variety of requirements in both enterprise and service provider networks.

The Move to Software, Virtualization & Standardization

Traditionally service providers have scaled their networks by adding more boxes, but now network traffic is more dynamic and unpredictable, so network operators want to scale on demand, says Ashish Jain, director of solutions marketing at GENBAND (News - Alert). Software, SDN and virtualization allow for that, adds Jain, whether we’re talking about SBCs or any other network functionality.

Sangoma, a pioneer in the software-based SBC, sees software as step one in the move to transforming the network to meet next generation requirements. Nenad Corbic, vice president of engineering at Sangoma, says step two is virtualization and having software containers you can push to Amazon and other clouds, said Corbic, adding Sangoma’s software works with Citrix XenServer, Microsoft (News - Alert) Hyper-V, Oracle VM VirtualBox, and VMware, and that Sangoma is looking to do a push to Amazon service as well so users don’t need to build their own virtual containers. The third step, says Corbic, is NFV, which is a standardized version of this concept.

Many of the SBC vendors, most of which started out as appliance specialists, are now moving in this direction and already added software-only session border controllers to their portfolios.

Sonus Networks in October introduced the Sonus SBC SWe, which is the software-only equivalent of the company’s hardware-based SBC 5000 Series. David Tipping (News - Alert), vice president and general manager of the SBC business unit at Sonus, says that

customers are looking for solutions that include SBCs but some might not want to include hardware used in SBCs. Some want to use ACTA platforms, he says; others want use Sonus software to test market new offerings in out-of-region markets.

Alan Percy, director of marketing development for AudioCodes, which also offers SBCs in both appliance and software-only formats, says there are certain applications for which each type of SBC is a good match. SBC appliances are a good match for applications involving deep packet inspection and transcoding, he says, because those functions are most efficiently done by DSP chipsets, which are within the appliances. Pure software SBCs running on commercial-off-the-shelf hardware or a virtualized servers work well for SIP trunking applications for which the G.711 codec in use all the way to the customer site. In this case, he explains, the SBC is handling security and probably some kind of interoperability SIP header manipulation, call access control, registration management, and the like.

“So it’s up a layer,” says Percy.

Oracle, which early last year bought SBC pioneer Acme Packet, has had a software-based SBC for year or more, says Jonathan Zarkower, who’s in product marketing for session delivery infrastructure at the Oracle Communications Global Business Unit. In addition to the appliance, server, and virtual machine SBCs it offers today, Oracle is working on a network functions virtualization solution, says Zarkower. The NFV product is in trials but that the commercial introduction of it is far down the road. This new NFV effort relates to core IMS products and controls, he says, and also ties into the concept of software-defined networking. Oracle already has an SDN product on the market, he adds.

Zarkower goes on to say that there’s an ongoing discussion in the industry about the idea of decomposing SBCs. Some vendors have made arguments that media (transcoding, etc.) and signaling functions could, and maybe should, be in two different elements, he explains. Some argue that signaling is growing at a much higher rate than media, he continues, indicating he’s skeptical about that claim. In any case, as NFV and SDN become more mature, customers say, they want to decompose the two above-noted functions of SBCs, adds Zarkower. But he says that idea is not yet ready for prime time because it’s too complex given the antiquated protocol H.248 is still being used as a way to integrate traffic.

What’s Next with WebRTC

WebRTC is another important new development on the communications frontier in which SBCs – or, at least, SBC suppliers – are positioned to play a part.

“Right now this whole SBC market is really excited about WebRTC,” says Steven Johnson (News - Alert), president of Ingate, which sells E-SBCs, among other solutions.

Oracle this fall introduced a WebRTC session controller. Chris King, senior director of product marketing-communications industry at Oracle, says this new solution brings together Oracle’s SDP technology with Acme Packet technology. It allows service providers to support multiparty calls, and maintains session state, so if a connection drops it doesn’t affect the other connections. Oracle is targeting its WebRTC Session Controller both at service providers and an enterprises, at which WebRTC can be used to extend the unified communications experience within the contact center (WebRTC can allow for the escalation of a call from one medium to another, and to have the caller’s interaction up to that time captured and displayed in the process) or just by regular enterprise users.

Meanwhile, GENBAND offers a WebRTC module, which is software that can be deployed with its SBC.

And a variety of other E-SBC and service provider SBC vendors, including Ingate and Sangoma, plan to introduce WebRTC solutions this year. Others have it on their product roadmaps, but are not offering guidance on commercial release dates.

Ingate is in development on what Johnson describes as WebRTC PBX (News - Alert) companion products that will allow companies to add WebRTC to existing SIP PBX environments.

He adds that putting a TURN server on the device enables enterprises to control and see all packets coming in to the SBC so they can ensure WebRTC applications get the required bandwidth. Service providers also can use this kind of device to stay in the call flow for WebRTC sessions, so they can generate revenue from those sessions, he says.

“WebRTC makes it much easier to do ad hoc collaboration sessions,” adds Johnson. “It makes possible the whole theory and promise of unified communications in a very simple way. It’s much easier to set up than SIP, and much easier and simpler than services like WebEx.”

Sangoma’s Corbic says that SBCs will play a central role in WebRTC, noting that the

legacy world is cut off from WebRTC without SBC, which can provide the translations between these old and new worlds.

“With Lync, WebRTC and video, all that is hitting the network, and the only technology that can keep up with all this technology is SBCs, because we’re in the middle of the network,” says Corbic. “The SBC is the glue.”