And another entrant jumps into the fray.

O2 (News - Alert) is going to try some VoIP services, according to the British industry journal The Register (News - Alert).

The service will be released under the brand of O2 Connect, The Register says, “while in America T-Mobile has opened up its Bobsled service to compete with Google (News - Alert) Voice.”

Don’t expect this to be a huge rollout quite yet, as The Register notes, “O2 Connect is just a trial run to see how the services work and how users react to them.”

Invitees will use the service to “make VoIP calls and send text messages from a smartphone over Wi-Fi,” The Register reports, adding that the commercial rollout is probably coming next year.

That’s in the UK. Here in America, T-Mobile (News - Alert) has updated its Bobsled service “to enable everyone to make free calls to any phone number in the USA, or Canada, from anywhere in the world, as well as connecting up Facebook (News - Alert) users on the move.”

It can handle clients for Android and iOS, The Register says, adding that you need the Web app to make free calls to US numbers, since “the mobile versions are still limited to connecting Facebook users, for the moment.”

O2 is playing coy about how much the VoIP service will cost, but as The Register notes, it is planning, as of this writing, to offer not only voice connections, but also SMS over Wi-Fi, “something other deployments have struggled with.”

You might remember Bobsled’s somewhat less than ideal debut. As TMCnet reported in April, media channels were buzzing with news of T-Mobile’s new free Facebook calling service, but the VoIP application was temporarily suspended only days after it was released on April 19, due to objections made by Facebook concerning the application’s design.  

Bobsled allowed Facebook users to make and receive free voice calls to their friends using the application, with no download necessary. Using the voice service, members can also record and post voice messages to their friends Facebook walls.

According to one claim from PC Mag, questions arose about the free voice chat service since it was developed to look like an app created directly by Facebook.