BT is bringing its Fusion converged fixed/mobile phone offering to the corporate market. 

BT Corporate Fusion works like a conventional mobile phone outside the office, taking advantage of GSM coverage and roaming. But inside the office it hooks into a company's IP telephony networks via Wi-Fi.

The advantages of fixed/mobile convergence are that employees can have a single number and single familiar device, making them more productive and easier to contact.

It is also cheaper for the employer because calls are routed via the lowest-cost route, often via corporate IP networks, reducing many call charges associated with mobiles.

According to research from analysts such as Gartner and IDC, up to half of all business calls are made from mobiles from employees' desks, quite simply because the mobile is more familiar than a high-feature desk phone and contains a personal contacts book.

The introduction fulfils BT's promise made back in May to bring Fusion to the corporate market.