Nokia was examining a switch from Microsoft to Google's Android operating system before it was bought out by the software giant, according to those close to the matter.
The New York Times reports that, even while Nokia and Microsoft were discussing the Finnish mobile phone maker's $7.2bn buyout, the smartphone company already had Android running on its flagship Lumia handsets.
The contacts, who are referred to as "two people briefed on the effort", said that Microsoft executives were aware of the project while discussions were on the table, but "another person" states that Nokia's potentially impending switch to Google was not a topic of the acquisition meetings.
However, it seems unlikely that Microsoft would have paid no heed to a fully-functional Android-based Nokia Lumia, as Google's Android mobile operating system is now resident on 79 per cent of the world's mobile real estate - and a growing number of other devices.
Nokia was due to reach the end of its Windows Phone licensing deal with Microsoft in 2014, after ditching its own Symbian and Meego operating systems in favour of a Windows Phone-only strategy in 2011.
While sales of smartphones have since crashed to just over three per cent of the company's sales, it dominates the Windows Phone market. A defection of Nokia to Android would have been a major blow to Microsoft.
In turn, though, Microsoft was reportedly considering a "Surface Phone", which would have been developed in-house as part of a Plan B.
Whatever the truth of Nokia's mobile backup plan, Microsoft's acquisition of the company's handset division, and the return of Nokia CEO Stephen Elop to the software giant (potentially also the new Microsoft CEO) will ensure the end of Nokia's Android experiments.