BT is gearing up for the launch of its Bluephone cellphone - which will be able to roam calls between the cellular network and a Bluetooth access point in the customer's house - despite doubts over its success.

"We're on track to launch in the next few weeks," said Ryan Jarvis, director of mobile products and partnerships at BT. Bluephone is the only known commercial service based on the operators' UMA (Unlicensed Mobile Access) convergence standard, but Jarvis claimed more operators are about to launch services.

Users want to converge cellular phones with the Internet, in order to get cheaper calls and useful features. The UMA standards let Bluephone connect calls using the customer's broadband service and a Bluetooth base station, but the call will be completed using the cellular network, and charged as a mobile call, rather than using the SIP protocol to hand it over to the Internet.

Although BT's pricing is not announced, the net effect is the user providing backhaul for the carrier, rather than save saving money. "It's a neat trick," said Dean Bubley of Disruptive Analysis.

Jarvis defended UMA: "Quite a few operators have UMA launch plans. Motorola has listed seven trials in Europe alone." No other actual products are announced at the moment, however, and other operators may wait till Wi-Fi enabled phones are ready, sometime next year.

Bluephone itself will be superseded by a Wi-Fi version, as we revealed in January. "There will be fifteen GSM/Wi-Fi handsets available by June next year," said Jarvis. This year, however, only Bluetooth is viable for a commercial UMA product, as it allows BT to use cheaper smartphones.

Ironically, the UMA group itself is closing down just as its standard is about to reach the market. The group is folding its standard into the 3GPP specification which defines mobile phone networks. "UMA has reached final approval and is part of the 3GPP standard," said Jarvis. The emphasis will now shift to the Fixed Mobile Convergence Alliance (FMCA) in which operators determine how standards like UMA and SIP should be implemented in handsets.

UMA will be part of Version 6 of the 3GPP specifications, which means it will be a standard part of phone networks, after they have implemented the current specification, version 5, which includes HSDPA and the IP multimedia subsystem (IMS). These networks will, therefore, support SIP, which does a better job of convergence than UMA.

"UMA can be launched before a network is Release 6 compliant," pointed out Jarvis. Bluephone itself will be implemented on Vodafone's system, and calls will be managed by UMA controllers added to the network. "A UMA network controller is effectively a base station controller that controls the access points in people's houses," said Jarvis.

The closure of UMA means nothing more than it has done its job, said Jarvis. "It's like closing the Labour election campaign office down after the election. It's done its job."