Microsoft has a less than stellar track record when it comes to mobile. The Nokia name has been all but phased out since the purchase of the firm's mobile device business, and recent handsets have adopted the Microsoft Lumia brand.
19/10/16: Rumours are circulating that we might see the Surface Phone at Microsoft's 26 October event. While it's likely much of the run-time will be given over to the announcement of the Surface All-In-One desktop PC, we also expect Microsoft to talk of its continued vision for Windows 10. It's likely that part of those plans will involve the perfected version of Continuum mode, and in-turn Surface Phone.
Whatever happens, we don't have to wait long for the truth.
26/09/16: Microsoft has filed a patent for "fingerprint detection with transparent cover". Sources claim Microsoft has developed a fingerprint scanner that's integrated into a transparent sheet, thereby avoiding the bulk usually associated with a sensor module.
12/09/16: We've long wondered whether a Surface-branded phone would signal the end of the Lumia line, WinBeta citing an anonomous source, claim Microsoft plans to "end sales" by the end of the year. If true, the company has at least had some success with Surface, which it will hope to replicate.
Kevin Gallo, director of Windows Developer Platform at Microsoft, alluded to the handset's existence in June when he spoke of plans to develop smartphones targeting the business sector.
What follows is everything we know about the Surface Phone so far.
We're told to expect an aluminium and magnesium unibody, the same combination favoured by Lenovo for the latest Ideapad 710S.
The image above is from prolific tipster 'Nokiabar', who has a reliable record when it comes to leaks. He has previously spilled the beans on the Lumia 650 and the cancelled Lumia 850.
The rumoured specifications are impressive to say the least, so we'll take them with a pinch of salt. Microsoft will offer three Surface Phone variants, the lesser of which will come with 3GB or 4GB of RAM and 128GB of storage.
The other two models will scale up to 6GB/256GB and 8GB/512GB. MicroSD expansion might also bolster the already generous storage options.
The OnePlus 3 made headlines with a colossal 6GB of RAM, and if we were the betting sort we'd wager that some of next year's high-end phones might match this. So it's plausible that Microsoft could follow suit, but an 8GB phone currently feels a long way from reality.
Microsoft could use the Qualcomm Snapdragon 830 to run the show, and we should expect liquid-cooling technology, plus a super-sized 5.7in panel with an impressive 2K resolution.
It is said that the Surface Phone will support the Continuum software used in Microsoft's Lumia 950/950 XL. Continuum turns the phone into a big-screen projector, allowing it to connect to an external display such as a TV or monitor.
The new phones are expected to have USB Type-C ports, a fingerprint scanner and Microsoft's Surface Pen peripheral. The top-end model might incorporate a 20MP Carl Zeiss sensor in the rear camera.
Early reports suggested that Microsoft's next smartphone will break cover before the year is out, but there are also rumours that production was halted to accommodate Intel's Kaby Lake processors.
There are arguments for both. An end of year release would capture the holiday market and serve as a counterpoint to big hardware releases from the likes of Apple and Samsung.
However, waiting until next year would allow Microsoft to tie the handset into the rumoured Surface Pro 5 and Surface Book 2 launch. We hope to see Windows 10 Redstone 2 around that time too.
If the 2016 launch is chosen, we'd expect Microsoft to hold a hardware event in October to announce the release.
Microsoft's last attempt at grabbing even a sliver of the smartphone market was the Lumia 950 XL, released in October 2015.
It cost £549.99 at launch but has since been reduced to £336.99. If Microsoft wants to even stand a chance, the upcoming Surface Phone(s) need to be priced competitively.
We've heard that prices might start at $699 for the lesser model, reaching as much as a whopping $1,099 for the top-spec version.