A Microsoft patent that went public on Monday outlines a foldable mobile device that plays double duty as both a mobile phone and a tablet.

First spotted by MSPoweruser, the device is described as having a flexible hinge that would give it 2-in-1 capabilities. Some of the sketches also show the device in "tent" mode, kind of like you see with Lenovo's popular Yoga 2-in-1 offerings.

What's particularly interesting here, as The Verge points out, is the fact that Kabir Siddiqui is listed as the inventor on the patent application. Siddiqui is also responsible for patenting some of Microsoft's other mobile device features such as the Surface kickstand and the Surface camera angle.

The device depicted in the patent bears an uncanny resemblance to another Microsoft product you may have heard of.

Codenamed Courier, that device was to feature two displays that fold together - much like a standard book, but with screens instead of pages. News of the Courier first broke in 2009 ahead of Apple's iPad launch but ultimately got the axe in early 2010, perhaps because flexible display technology simply wasn't mature enough.

The general consensus with Microsoft's latest patent, which was filed in October 2014, is that it could serve as the foundation for a Surface Phone. Then again, it could be just another one of the thousands of ideas that Microsoft patents that never makes it into production.

Perhaps we'll learn more at Mobile World Congress late next month.