If there was any doubt that the vision of one unified Windows 10 OS running on Phone and PC is dead, the latest Insider version of Windows 10 Fall Creators Update should lay all of that to rest.
A comparison of the WinRT APIs between Windows 10 build 16188 (pre fall creators update) and Build 16193 (post fall Creators Update) shows that Microsoft added a large number of APIs to deal with cellular data connectivity, but specifically removed APIs dealing with phone calls, such as call blocking, voice mail, phone line, phone call origin and many more.
In fact public enum Windows.ApplicationModel.AppService.AppServiceCallerCapabilityStatus now defaults to
HasCapability = 0,
DoesNotHaveCapability = 1,
CapabilityStatusUnavailable = 2
As Microsoft places increasing emphasis on bringing old-style Win32 apps in the store and bring more and more of their services to iOS and Android it seems increasingly clear that Windows 10 Mobile and phone-style devices are no longer part of the company’s roadmap, with even Joe Belfiore merely saying phone will continue to be supported, rather than being further developed.
It seems even when Microsoft finally brings Windows 10 on ARM it is unlikely these devices will support making phone calls, meaning users will likely still need an additional iOS or Android handset, which with increasing Microsoft support should no longer be the end of the world for Microsoft fans.