UK mobile phone network O2 is launching a trial of a new VoIP service for customers to use across WiFi networks.

O2 Connect will allows smartphone users to use voice and text services from their normal mobile number to any UK mobile or landline number. It will initially be available via a dedicated app on iOS and Android devices only, though it plans to roll it out to other devices in the future if the initial trial proves successful.

O2 Connect Trial Load Screen2 O2 to trial new VoIP app in the UK, giving customers free calls over WiFi

The trial will start this month and will be limited to 1,000 users in the first instance to assess how the service can best be deployed across the network. It will be by invitation only, covering both consumer and business customers, and the trial will also be extended to attendees at the Wired 2011 event later this week. The initial premise is that calls from O2 customers using the app, to other O2 customers & landlines, will be free.

Although it’s just a trial to begin with, this could be indicative of the way mobile networks choose to go in the future, with applications such as Skype already offering consumers free mobile-to-mobile calls. This is just a proof of concept at the moment, and it’s not exactly clear how the final proposition will cater for cross-network calls – whether they’ll be free, or perhaps paid by the recipient.

O2 Connect is the latest in a series of developments from O2 Labs, introducing new services with beta testing and customer involvement in the development process. Richard Porter, Head of Consumer Mobile Products for O2 UK says:

“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.”

O2 says there are key differences between O2 Connect and other similar services, for example your normal mobile number is your ID, so there’s no need for usernames or other unique IDs.

O2 is the commercial brand for Telefónica in the UK, Ireland, Slovakia, Germany and the Czech Republic, where it has almost 60m customers. And with 22m in the UK alone, it is the country’s second largest mobile network after Everything Everywhere.

A few weeks ago, Telefónica announced its new global unit, Telefónica Digital, that will focus on its growth in the digital world. Based in the UK, it also has regional centres in Silicon Valley, Sao Paolo, Tel Aviv, Madrid and Barcelona.

This is certainly a big move by O2, and it will be interesting to see how this initiative unfolds throughout its roll-out. We can perhaps expect to see similar moves into the VoIP space by other mobile networks in the future.