Telecom Italia (TIM) has decided not to use unlicensed mobile access (UMA) for its fixed-mobile convergence (FMC) service Unica, and has relaunched the service with a homegrown SIP-based solution. (See Telecom Italia Launches FMC.)

The operator made the technology change because of Italy's regulatory regime and the limited availability of UMA-enabled handsets.

Telecom Italia launched a limited commercial FMC service earlier this year with UMA network controllers from Motorola Inc. (NYSE: MOT). But the service got tangled up in a regulatory tussle -- along with Vodafone Italy 's home zone service -- at national regulator Agcom . (See FMC Fusilli and Italian FMC Face-Off.)

After months of investigation, Agcom decided that Telecom Italia would have to provide a wholesale version of Unica so that competitors would have a chance to provide a similar service. And Agcom gave Telecom Italia six months to create a wholesale service -- not a desirable scenario for the Italian operator.

In addition, Telecom Italia felt constrained by the limited number of UMA-enabled handsets.

"We launched [earlier this year] based on UMA, but we left the technology," says Enrico Roberto Polese, technology program and process management at Telecom Italia Lab , speaking at Informa Telecoms & Media 's Developing Converged Services conference in London.

So in October, Telecom Italia relaunched the Unica service, this time based on SIP, as part of a quadruple play offering. Telecom Italia Lab developed the client that is loaded onto dual-mode WiFi/cellular handsets. The handset can then determine whether to place calls over WiFi networks or the cellular 3G or GSM networks.

Theoretically, the Unica service can be used with any Symbian handset, but Telecom Italia has launched with just the Nokia Corp. (NYSE: NOK) E65 for now. Telecom Italia says the service will work on about six or seven Nokia handsets in its portfolio. Unica will also soon be compatible with Windows Mobile devices, once a small technical glitch with volume control is resolved.

Telecom Italia is in discussions with Nokia about pre-installing the Unica client onto its dual-mode phones.

The SIP-based service will work on more handsets -- many of which are 3G devices -- than a UMA-based service. But the drawback is that there is no handover between the cellular and WiFi networks with SIP.

"There is no integration between the two networks," says Polese. "Convergence is in the handset."

Ultimately, Telecom Italia wants to base its FMC services on IMS with voice call continuity (VCC). The operator has tested IMS-based VCC in its lab, "and it works," according to Polese.

Early next year, the Italian operator will launch an IMS trial, which will include some tests of VCC.

"When we look at the customer, convergence means better tariffs at this moment, and that's a problem," says Polese. "From a technical point of view, we believe IMS will be the converged platform."

Other operators that have rolled out UMA-based FMC services, and so far stuck with the technology, include BT Group plc (NYSE: BT; London: BTA), Orange France , Telia Company , and T-Mobile US Inc. . (See Orange Doubles FMC Customers, Orange Builds on FMC Base, Swedes Are Home Free With FMC, Gateway Key to BT's Fusion Flop, and T-Mobile Launches UMA in USA.)

News of Telecom Italia's decision comes as UMA edges closer to becoming a 3rd Generation Partnership Project (3GPP) standard technology. (See UMA Nears 3GPP Approval.)

— Michelle Donegan, European Editor, Unstrung