Over-The-Top (OTT) messaging player Viber is running a limited trial of call termination, according to Techcrunch.

The trial, which involves delivering calls to around 400 Viber users, could evolve into a revenue generator for the company in the future, explained CEO Talmon Marco (pictured).  Its basic voice and messaging app is free to users.

Call termination in itself would bring in revenue but Marco suggests the trial is more about testing new value-added features, Viber’s favoured route to monetisation.

“We’re not testing revenue models, we’re testing our ability to deliver calls this way with high quality, along with many other aspects of connecting the Viber system to regular telephony,” he said. Users could opt to receive calls this way or not, a possible feature in itself.

Marco’s comments follow an interview given to Mobile World Live earlier this year when he said charging for value-added services was its chosen route to monetisation. He dismissed advertising as a possibility.

Viber could offer its popular app to mobile operators as a means to promote larger data bundles. Earlier this year, it signed such a deal with Indonesia’s Axis, which is owned by STC.  Offering additional voice features on an operator’s network is another possible value-added service.

The call termination test was originally uncovered by Geektime and then confirmed by Techcrunch. Viber has signed deals with several operators for its call termination trial.