BT has announced "enterprise fixed-mobile convergence", a business version of its domestic Fusion mobile/cordless service.

The Enterprise FMC service will give users a mobile handset that uses Wi-Fi to become an extension to an IP-based PBX when in the office, so users get cheaper calls and deskphone functions in their workplace.

The project is a larger scale version of BT's Fusion service, which BT hinted at the launch in June 2005. Aimed at consumers and small businesses, Fusion uses a Bluetooth connection for broadband calls that are about 50 percent cheaper than landline calls, a BT spokesman said.

Larger enterprises are demanding converged services which combine Wi-Fi, Bluetooth and broadband connections for cheaper and more mobile voice and data services, and deliver deskphone functions, said BT.

Alcatel will build the infrastructure for the service (and has posted a press release), with help from Lucent, which will provide the VPN firewall and security products.

The nuts and bolts are not yet completely announced, although Alcatel has been involved both with BT's UMA-based Fusion service, and the SIP-based BT Communicator VoIP service available with Yahoo's instant messenger.

The service will use dual-mode Wi-Fi GSM (Global System for Mobile Communications) phones, such as the Nokia E-61, in use which is also the first phone for Truphone, a consumer converged service to be launched at VON next week.

When in range, the phones use a cheaper Wi-Fi connection for VOIP (voice over Internet Protocol) calls while also switching to the mobile network.

BT said the service's "intelligent routing" feature can use information stored in a device, such as a calendar, and forward calls when, for example, a person is in a meeting.

The new service will first be available in the UK early in 2007, with plans to expand it to France, Germany, Spain and the Netherlands, the spokesman said.