BT's Fusion service (formerly known as Bluephone), launched this week, is officially the first converged fixed/mobile phone service, but the company can't rest on its laurels. The landscape has now changed, and future services from BT and other operators could be very different.

Fusion is, as Steve Andrews, group chief of mobility and convergence at BT, said, "just a start."

One foot in the future
Most operators are waiting for cell phones with Wi-Fi built in, before launching a converged service. BT has launched a Bluetooth-based service, in order to get into the market now and gauge the response. The handset it has been launched with Motorola's V560, is an unremarkable phone, not some high-tech device.

The fact that only 400 BT Broadband customers will get it before the roll-out in September, makes it clear that BT sees the needs to test out such a new concept. However, plans to offer the chic Motorola RAZR suggest, the Bluetooth edition of Fusion is expected to have a considerable lifespan.

BT is very clear of its reasoning. It decided to go with Bluetooth because Wi-Fi capable phones are too far off. While some high-end devices are appearing with both Wi-Fi and cellular connections (including one from Motorola), they aren't yet viable for a consumer service like Fusion, says Ryan Jarvis, director of mobile products and partnerships at BT: "People say there are lots of converged handsets, but they need to be at the mid-price point - and they aren't there today." Battery life is also an issue, he points out. "Wi-Fi has a worse talk time today."

Wi-Fi is definitely the future, and the consumer edition of Fusion has Wi-Fi built into the hub. For now, that's just for customers to link their PCs to their broadband. BT will offer a Bluetooth-only hub for those that have Wi-Fi set up that they don't want to disturb, but this is not being promoted at all - because when the handsets are ready, the Fusion hub is set up to deliver a converged service over Wi-Fi, with just a change of handset.

Wi-Fi for consumers - next year
The Wi-Fi version of Fusion will use same UMA (unlicensed mobile access) technology, but use Wi-Fi instead of Bluetooth for the handset connection. As with today's Fusion, UMA will hand the call to the Vodafone network (which BT has an MVNO agreement to use) for connection.

The Wi-Fi version is about a year away, says Jarvis, and at the launch date, the Wi-Fi handset will allow users to make calls on all of BT's Openzone Wi-Fi hotspots, as well as their home hub. We expect hotspot calls to be priced at landline rates, just as outgoing calls are now, but Jarvis points out that there is enough intelligence for any pricing scheme BT wants: "Don't assume any pricing."

The handset will not work on other Wi-Fi hotspots though - except possibly those with an Openzone roaming agreement. Using it on other hotspots would require user intervention, and that's not the kind of product this is. "We don't want users to be aware of the technology," said Jarvis.

The thing to look for is international roaming. BT would have no trouble enabling the phone to use hotspots abroad cheaply, making this the Skype for people who find Skype too technical.

Bluetooth - and the practical details
One detail that wasn't clear at the launch was how the Bluetooth version works with headsets - an essential for a mobile phone that people will be using in cars.

"The Fusion phones will include a corded headset, which works in both environments" says Jarvis. The phone can only pair with one Bluetooth device at a time, however: "The phone can be connected to a Bluetooth headset as usual, when the user is out and about," says Jarvis. "When it is in range of the hub, it won't roam to the Bluetooth hub, if Bluetooth is already in use." This limitation will go with the Wi-Fi version.

In use, at the moment, the phone roams easily without any user intervention. The voice quality over Bluetooth is easily as good as on the mobile network - or better. The whole of any call is billed at the rate it started at, so in fact, the system may well only roams when one service is not available.

When it hands over, the user hears a trill. "The sound is maybe 100-200ms long," says analyst Dean Bubley of Disruptive Analysis. "Perhaps its there to mask a break in the connection, but it is unobtrusive." It's also a feature, as it alerts you, for instance, that your next call could be made at a better rate.

The enterprise version won't be UMA
All this is fine for consumers, but very much less than most businesses will want. BT has an enterprise version (which may or may not be called Fusion) under development, and it will be very different.

"We've gone out to tender, on this product," says Jarvis. The enterprise version will be based around an IP PBX, and we can assume it will work with existing PBXs. "It will support PBX and Centrex systems and will integrate with corporate dialling plans," says Jarvis.

What it won't be is UMA, however. Jarvis would not confirm this but UMA would clearly not make sense. BT is installing a 21st century network, supporting the SIP and IMS standards (read Wi-Fi to Cell - here comes a new approach); it would be very strange indeed to have a product that could connect calls in IP form, but routed them over Vodafone's mobile network instead. " BT's core network is the heart of BT's future," said Jarvis.

"When SIP becomes a global open standard, we will migrate the consumer SOHO products and corporate products to it," said Jarvis.

Perhaps the biggest surprise may be the delivery date. "Enterprise customers aren't so price-sensitive," said Bubley. "There may be Wi-Fi capable handsets available at an enterprise price point before the end of this year."