The European Commission is understood to be probing the practices of mobile operators who block or restrict internet telephony (VoIP) applications on their networks.

The EC has sent questionnaires to a number of unidentified European carriers asking for information on their tools and techniques for filtering and blocking VoIP traffic. The assumption is that the authority is looking into whether such activity is in breach of competition law.

For the most part mobile operators have had an uneasy relationship with mobile VoIP. When the technology first cropped up on wireless networks many operators swore they’d never let it loose on their own infrastructure for fear of cannibalising cellular voice revenues.

A well know spat between T-Mobile UK and mobile VoIP player Truphone highlighted operator apprehension, although T-Mo claims that the tussle was actually over interconnect fees.

But more recently the tide seems to be turning. The UK’s perennial disruptive influence, 3 UK, has teamed up with Skype to actively promote mobile VoIP, while Fring has scored a landmark deal with mobilkom in Austria.

The fact that the Austrian service will use proper VoIP over 3G, rather than a circuit switched call via a VoIP gateway as per Skype, makes this a big deal as one of the first such VoIPo3G partnerships in Europe and an important signal for the future.

Commenting on the Fring deal last month, Dean Bubley of Disruptive Analysis, said, “mobile operators should look to partner with 3rd-party VoIP specialists, in order to gain early experience (and leverage their software experience) in delivering packet voice on cellular networks.” Ultimately, the analyst expects mobile operators to U turn on their initial VoIP hostility and VoIP advocates.

In the summer, industry analyst IDC, said voice as an application would be at the forefront of the evolution of personal IP communications. Already, with the explosion of widgets, voice is becoming embedded in sites, applications, and other services, sometimes by third party developers but also by the original provider. And the analyst believes IP communication clients for devices, such as Truphone and TalkPlus, are integral to the growth of personal IP communications.

While some web-based services offer a mobile platform via bridging capabilities over the cellular network, many thin clients are looking to provide an end-to-end VoIP experience via the data network. IDC reckons the proliferation of emergent MIDs (mobile internet devices) will be dependent on these IP communications clients’ voice communications.