Telefonica’s commercial mobile operator O2 has announced that it will begin the UK trial of a new branded mobile VoiP application that will allow users to make calls and send texts via WiFi.

The app will enable users to make and receive calls using their own number to any UK mobile or landline number. Callers will be able to use it from anywhere in the world, provided they are calling a UK number.

Similar to T-Mobile’s US Bobsled service, which recently updated its service to include US and Canada-based mobiles and landlines, on top of the Facebook-routed voice calls it originally offered, O2 Connect shows how mobile operators are innovating around the threat posed by other VoiP services like Skype and Google Voice.

The consistently improving quality of mobile data networks will continue to allow innovations like these to take place.

While there is, as yet, no information on how much the O2 service might cost, it is thought that use of the app will fit around existing pricing structures.

The service, O2 Connect, is the latest development from O2 Labs. It will initially be available on iOS and Android smartphones and will subsequently roll out to other devices.

A limited number of people will be invited to take part in the trial to assess how this type of service can be deployed to customers as well as participating in the development of new features, the firm said today.

“This trial will allow us to explore the potential of delivering VoIP services to customers. We hope to launch O2 Connect as a commercial service in 2012.” said Richard Porter, Head of Consumer Mobile Products, O2 in the UK.