New features for voice on Wi-Fi networks have landed Meru Networks the world's biggest converged voice deal.

"It's a landmark deal for fixed mobile convergence," said Joel Vincent, director of product marketing at Meru. "Osaka Gas was a hotly contested customer in Japan." The deal will link up to 10,000 staff at fifty offices of Osaka Gas, one of Japan's largest utilities, and use a "converged" handset that can make mobile calls on the Japanese FOMA system, and in-building Wi-Fi calls using SIP (Read Mobile operators wield converged phones against the landline).

Although Meru has demonstrated converged voice in Europe, the deal is unlikely to be repeated outside Japan for some time, because it relies on services from Japanese operator NTT DoCoMo, launched last year.

In the UK, BT is working on a business-oriented follow-up to its domestic converged service, Fusion . Although BT has not announced what technology will be used, it is expected to be evaluating Meru.

The deal is also a vote of confidence for Meru's wireless architecture, which differs from more established wireless switch vendors such as Cisco's Airespace subsidiary and Aruba. Meru puts adjacent access points on the same wireless channel, and uses software to sort out co-channel interference issues.

Meru beat off both Aruba and Airespace, even though Airespace has an OEM partnership with NEC, and has specific extensions to suit the NEC handsets which will be used by NTT DoCoMo at Osaka Gas, said Vincent. "Even with [Airespace's] advantage of owning both ends, we still ended up ahead," said Vincent.

Osaka will be use some voice software, that Meru is now launching as a product. This includes call admission control, call balancing, and dynamic error correction.

Call admission limits the number of calls that can be put through a given access point: "Otherwise, if an access point is supporting 15 calls, the 16th one will degrade quality for everyone," said Vincent. Further calls will be connected to nearby access points, given a busy tone, or (at Osaka, where the handsets are dual-mode) sent over the cell network.

Call balancing moves active calls around to even out the number of calls at each access point, and prevent overloading. For error correction, the software covers gaps caused by lost packets, by replicating the previous packet. "One packet lasts about 20ms., so it won't be noticeable," said Vincent. "It's a common technique that has not been applied to voice over WLAN before." The Voice Services Module will be available now, and costs $20 per user.

Although converged services are not available in the UK, Meru's products are already used for voice over WLAN here: "These guys make the only proper working Wi-Fi VoIP solution as far as I can see," said one system integrator on the Voip User discussion board, who is using two Meru access points to support up to 50 users in a UK office.