Red Herring today looks at mobile operators' investment in Unlicensed Mobile Access (UMA) as a potential competitor against the growth of free VoIP services like Skype.

"Wireless phone companies, worried their customers may start using VoIP services like Skype as Wi-Fi-enabled phones become commonplace, are lining up behind an alternate technology called UMA," the article states.

UMA offers the advantage of Seamless mobility between GSM and Wi-Fi networks, and allows wireless operators to retain control over (and payment for) the call.

And services like this are already heading into the market: the UK's BT Fusion uses Bluetooth as an access technology instead of Wi-Fi. Sweden's TeliaSonera has plans to offer a commercial UMA service in the second half of this year.

Still, some question whether consumers will go for UMA over a free option like Skype. "UMA is a technology developed by carriers that just does not have a business justification," says William Quigley of Clearstone Venture Partners.