Rebtel has announced the beta launch of free iOS and Android SDKs that enable developers to integrate calling capabilities into their apps.

The company is testing the SDK with a B2B company, a dating service and a language learning provider – but says that it can be integrated for customer service, business communications or simply to offer a better experience.

Game developers could give players the opportunity to phone a friend without leaving the platform, the company says, or dating apps could offer real-time voice calls for better matchmaking possibilities.

The company says that the integration, which will deliver free HD-quality app-to-app calling over Wi-Fi or 3G, only takes 15 minutes and will be demonstrated live at the AppNation conference in San Francisco.

Rebtel currently has 18m users globally of its over-the-top data call service, which promises free or cheaper calls delivered specifically for mobile. It is mainly used in the US.

“There are millions of apps in the app stores, with games and social networks some of the most popular. A voice layer can give a much richer experience for users, adding value, increasing loyalty and reducing churn,” said Rebtel CEO Andreas Bernstrom.