Avaya highlights Sipera's Session Border Controller in announcing the deal.

Avaya will acquire Sipera for an undisclosed sum, the comparnies announced this morning.

Sipera made its name in security software for SIP-based systems (hence its name), and has a research lab, VIPER, that produced security assessment tools and released periodic reports on communications security vulnerabilities.

But in announcing the deal, Avaya's top bullet point was the fact that Sipera has a Session Border Controller product that will now become part of the Avaya portfolio. Avaya has been selling an SBC that it OEMs from Acme Packet. (Here's our coverage of Sipera's announcement of its SBC at Enterprise Connect 2011.)

The deal therefore could represent a shift in the enterprise SBC market, at a moment when E-SBCs are emerging as a key component of enterprise real-time communications deployments, especially in SIP trunking deployments. Acme Packet has been far and away the market share leader in SBCs, with over 50%, and its SBC works with all the leading enterprise communications platforms.

However, enterprise vendors including Cisco and Siemens (and now, it seems, Avaya) have released their own SBCs, and in the case of Siemens, the SBC only talks to Siemens platforms on the enterprise side of the device. It remains to be seen whether the Sipera SBC will work only with Avaya Aura--but it seems unlikely that anyone other than an Avaya customer would buy an Avaya SBC.

So long-term, does the SBC become simply another element of a UC vendor's platform--an appliance, a virtualized application, or some other component? Or does it become a standalone appliance that, itself, becomes more of a center of gravity for communications session management, taking on much of the role of the PBX? This latter theory was advanced in this No Jitter post by Mykola Konrad of Sonus Networks, which makes SBCs. Konrad's vision of the SBC would be congenial to companies like Acme Packet as well--those whose business model relies on the standalone SBC.

So was this really a defensive move by Avaya? We don't know how much they paid for Sipera, but right now Avaya has filed for an IPO. Though other big tech IPOs like Groupon have been shelved amid a terrible IPO market, Avaya hasn't announced any such delay.

Bottom-line is that this deal is not a blockbuster, but it's significant as an indicator of where the market for an emerging product category--the Session Border Controller--may be headed. And it may yet have something to tell us about Avaya's future directions.