A new build of the Windows Insider programme is fueling speculation of the rumoured Surface Phone. Parts of the Windows 10 preview contain API references to telephony services; something that is different from what is commonly contained in Windows builds.
Some of the functions referenced in the discovery include dialing numbers and contacts, blocking withheld numbers, support for Bluetooth headsets and speakerphone mode. Functions that were previously not present on Windows systems; which mainly featured support for data connections over cellular modems.
Ars Technica also shared that Redditors spotted references for video-calling support, using either 3G or LTE. Speculation is that the APIs are just carry-over from Windows 10 Mobile and a mistake from compiling the latest kernel, which is slated to be featured in upcoming Windows Update called Redstone 5.
That said, the APIs match those found in Windows 10 Mobile. A project that has been abandoned. It’s more likely that some Microsoft engineers left the code in the project after a consolidation exercise; which sounds like the most plausible explanation. Especially since Microsoft has not shown any signs of being interested in the mobile space any longer.
(Source: Ars Technica)