Despite some assumptions to the contrary and the partnership between the two companies, Skype confirmed to SlashGear that the company is not powering Facebook Messenger’s new internet calling feature, which was recently opened to Americans with iPhone devices.

It’s unknown who is powering Facebook Messenger VoIP, and Skype had been a guess due to the partnership between the two that’s been in existence since 2011, when the two partnered to bring video calling to Facebook’s chat conversations via desktop browsers. Since then, Skype has been integrating Facebook with its desktop software, but has recently started focusing more on its own mobile apps.

Facebook has been trying to strengthen its mobile presence and VoIP is just another piece of that puzzle. Since most of its users access the site via mobile, it makes since for the company to try and monetize the usage of the site on mobile phones and tablets.