One of the few providers using the UMA scheme to combine Wi-Fi and cellular service using dual-mode phones has ditched the standard in favour of a more open SIP-based approach, leaving BT's Fusion, and France Telecom's Unik supporting a lacklustre approach.

Part-way through launching Unica, a converged phone service based on UMA (unlicensed mobile access), in which a dual-mode handset shifts between the cellular network and the subscriber's indoor Wi-Fi service, Telecom Italia switched, and launched a service which achieves the same thing through SIP. The reason is because of a lack of handsets, and barriers raised by the Italian radio regulator, according to industry site Unstrung."We launched [earlier this year] based on UMA, but we left the technology," said Enrico Roberto Polese, Senior Project Manager at Telecom Italia Lab , speaking at the Developing Converged Services conference in London.

"I suspect a couple of other operators may also dump it - but on the flipside there's possibly a few more launches to come," said Dean Bubley of Disruptive Analysis. "Mind you, my original 'pessimistic' forecasts turned out to have not been pessimistic enough - the original forecasts I put out in mid-2005 were for 2m UMA homes (average 1.2 phones / house) at the end of 2007."

Telecom Italia launched a limited version of the UMA service earlier this year, using Motorola controllers commercial FMC service earlier this year, but faced pressure from Agcom, the Italian regulatorm to open the service up to competitors by providing a wholesale version of the service within six months. The new Unica is a quadruple play offering, using a SIP client developed by Telecom Italia, and built into dual-mode handsets. It's going to be available on other Symbian handsets but is on the Nokia E65 for now - with plans for other Nokia devices and Windows Mobile handsets.

The service has a "hard handover", which means calls can't roam from one service to the other. Telecom Italia plans to offer that later on, by moving the service to the IMS platform which is being implemented on 3G networks, but for now considers the service is ready go with users having to redial if they enter or leave the house while on the phone.

The defection leaves BT's Fusion (which has taken two years to reach around 50,000 subscribers, and the more successful Orange Unik in France - which reached 100,000 subscribers in a year, as well as a service from TeliaSonera in Sweden. Moving from UMA to SIP is not necessarily a recipe for success, however, as T-Mobile in Germany cancelled a non-UMA service after five months due to lack of interest.

"The main UMA 'winner' at the moment is Orange, launched/launching in four or five countries, and getting on towards a million users," said Bubley. "T-Mobile US seems to be getting a bit of traction on its Hotspot @ Home service, and there are a couple of others out there."

UMA providers, meanwhile, have responded to the general lack of success at the handset level by shifting their attention to building UMA into femtocells - small indoor base stations that use broadband for backhaul but use 3G indoors, not Wi-Fi. "Femtocells are definitely the focus for UMA at the moment - they really want to have it pushed as a standard at bodies like the Femto Forum, although they certainly don't have overly broad support from all the femto suppliers," said Bubley.