Start-up Agito Networks can cut company's mobile bills with a system that hands voice calls over quickly and accurately between company Wi-Fi and the cellular networks, the company claimed.

Agito's system uses RF-location to tell when a user is approaching predefined points at the limit of the company's Wi-Fi coverage. A client on the handset co-operates with the company's RoamAnywhere router, which integrates with the company's IP PBXs, so phone calls can be handed over between the Wi-Fi and cellular networks.

The handover takes less than one second, which is much quicker than competitors, according to Pejman Roshan, Agito Networks' vice president of marketing. "Some solutions centralise call control decisions in the appliance - we take a different approach, distributing processing to the clients." This is quicker and also more scalable, he explained, since each handset can handle its own calls.

The system allows administrators to set up "RoutePoints" by simply clicking a button on a normal dual-mode handset to tell the system when they are at the front door. Other Agito-enabled handsets will then auto-detect that point.

Rival technologies such as DiVitas have trouble scaling to larger companies, and use less effective location technologies, based on signal strength, said Roshan. Agito claims its system will scale to 1000 users and beyond, while rival systems top out at about 250.

"RF is not constant," said Roshman. "It varies in time and according to building materials." Agito's founders are from Cisco, where they worked on location technologies to enable the detection of rogue access points, he said.

The system will improve battery life, by switching off the Wi-Fi when the phone is definitely out of range of the company's Wi-Fi system, said Roshan. It also allows for users to apply policies - so that calls can be routed to voicemail instead of the mobile when they are not on duty.

The system is in trials, and will be launched in the US at the end of 2007. A model that supports 100 simultaneous calls will cost $9,995, and one that supports 1000 will cost $24,995, said Roshan. It won't be available in Europe until the end of 2008, due to localisation issues.