Covergence has introduced a session manager for unified comms that is delivered as a virtual appliance. The virtual session manager can handle tasks such as VoIP call routing, security and interoperability for enterprises or carriers, the company said.

Called CVA-50, the $5000 (£2,560) virtual appliance is delivered as a pre-wrapped VMware machine, making it rather cheaper than buying a hardware session border controller, or SBC, said Rod Hodgman, Covergence's marketing VP.

SBCs are used to bridge telephony networks, deal with NAT traversal for firewalls, handle call admission control and so on. They can also improve VoIP performance by offloading the call managers of routine work such as device re-registration.

However, Hodgman claimed that CVA-50 is different because it is application-aware and can enforce business policies. That means it can also integrate, manage and handle policy-based routing for unified comms and comms-enabled applications, such as instant messaging and presence-aware office software.

"We come at this from a different perspective than most session border controllers, or SBCs," he said. "It's not just 'How do I make this work through a firewall?', it's a next-generation SBC that also does SIP normalisation for interoperability, say."

Although most often associated with VoIP, SIP is used to do session set-up for other types of comms as well.

He continued, "The average IP telephony vendor is bringing copper wire thinking to an IP world. Fifty percent of the classic SBC could and should be handled elsewhere - Cisco and co will do it in their routers. But that's only 10 to 20 percent of what we do, and you can't put our level of deep packet inspection into routers.

"You still need SIP decryption and policy on top of deep packet inspection - it is all about SIP interoperability, and control, and session set-up."

Hodgman added that the CVA-50 is the same software that Covergence currently sells in appliance form - one of its European customers is Interoute, an ISP which uses it to provide unified comms services for sale to its subscribers.