Start-up companies are fairly rare in telecom equipment these days, but one new firm believes it has carved out a niche in providing subscriber management for multimedia services, including fixed/mobile convergence.

Key investors apparently agree because Stoke this week announced both its third funding round and its new product, the Stoke Session Exchange (SSX) 3000, a multi-access gateway.

DAG Ventures led the $20 million funding round, which also attracted Kleiner Perkins Caufield & Byers and Sequoia Capital.

The SSX is designed to serve network operators in the era of multiple access technologies, including different types of wireless such as cellular, Wi-Fi, WiMAX, as well as fixed fiber, copper and cable, said Keith Higgins, Stoke’s vice president of marketing. It provides stateful session management for broadband multimedia services based on service provider and customer priorities, such as availability, price and location, and also provides security and quality control.

It will enable the kind of services now seen in television commercials from major providers showing phone calls, Web sessions and especially video moving from device to device, as the user does.

“The alternative to something like this is to use legacy platforms – three or four different systems with all the complexity of scale and management of those platforms,” Higgins said. “We are starting to see now RFPs emerge for access independent gateways. Just as they did in the core of the network, service providers want to converge the edge and have fewer devices.”

The system could replace gateways now used for subscriber management for discrete services, Higgins said, though more than likely it will be deployed initially to support WiMAX offerings and fixed-mobile convergence.

“Existing gateways [for wireless networks] provide the data connectivity for existing mobile phones, but they were designed for lots of low-bandwidth sessions, with no encryption, no multimedia and no mobility between networks,” he said. “Now, as you want to move between a cellular and a Wi-Fi network or a WiMAX to Wi-Fi network, we can manage that session.”

Current Analysis Analyst Joe McGarvey sees the SSX as a new form of “god box,” in that it combines multiple functions into a single, more efficient system.

“I mean that in a good way,” he said. “Convergence has been going on in the core of the network, but we’ve had all these different access technologies. This brings convergence to the access. They are a little bit ahead of the curve right now.”

It also brings together functionality now resident in multiple different systems, including Broadband Remote Access Servers (B-RAS), edge routers, subscriber management systems (SMS), and packet access devices that provide things such as encryption and network address traversal, McGarvey said. “I think there is some real validity to this kind of network access device.”

The system is scalable – it can be cost-effectively deployed for a customer base as low as 4000 and scale up to support 256,000 active sessions, Higgins said. Stoke doesn’t expect to see service providers rip out existing SMS gateways to install its system but does hope to gain the growth business of WiMAX deployment, and see traffic migrate to its system as fixed-mobile convergence takes hold.

Stoke doesn’t see itself taking on the industry giants, including Cisco Systems, Juniper Networks and Redback Networks, soon to be part of Ericsson, although all three play in the edge router space.

McGarvey believes Stoke’s approach to the market is a wise one, but admits the company could quickly become a takeover target.