Just ahead of the launch of Windows Phone 8, Nokia CEO Stephen Elop said he had "no indications" that Microsoft was building its own Surface phone, even welcoming Microsoft to join the ranks as "a stimulant to the ecosystem." Nokia has never made any formal risk statements that Microsoft could build its own smartphone, but this week the company's tone changed somewhat.

In a filing with the SEC, spotted by ZDNet, Nokia acknowledged that Microsoft could very well be building its own smartphone hardware. "Microsoft may make strategic decisions or changes that may be detrimental to us. For example, in addition to the Surface tablet, Microsoft may broaden its strategy to sell other mobile devices under its own brand, including smartphones. This could lead Microsoft to focus more on their own devices and less on mobile devices of other manufacturers that operate on the Windows Phone platform, including Nokia," says the filing by Nokia.

Nokia has never used such wording before, suggesting that the possibility of a Surface phone is a more serious consideration in Espoo than ever before. Nokia also acknowledges a new risk that Microsoft could reduce investment in Windows Phone or even discontinue it. Nokia states "if Microsoft reduces investment in that operating system or discontinues it, our smartphone strategy would be directly negatively affected by such acts." This scenario is far less likely than a Surface phone, but it's a new admission by Nokia regardless. The SEC filing is all related to risk, so such wording is common, but Nokia did not have the same statements in its previous filing last year.

Rumors emerged about a potential Surface phone late last year, but sources informed us that Microsoft was considering the option as a "Plan B." We're told that the same strategy is in place today, but that Microsoft is in the early stages of concept and prototyping what a Surface phone would eventually look like. That doesn't mean the company is committed to bringing such a product to market. Microsoft regularly prototypes hundreds of products it never launches, Courier is a great example of that. Still, Nokia seems to be more concerned about the prospects of Microsoft extending its hardware reach to phones, so perhaps Microsoft's "Plan B" is moving forward ever so slowly.