It is obvious that there should be some penalties there, if Nokia decides to abandon Windows Phone and switch to another smartphone OS. And we already know that Nokia has made some firm commitments on the amount of Windows Phone licenses it must buy from Microsoft each year, no matter what.But is there some exclusivity clause there, that would prevent Nokia to adopt some other, third party smartphone OS, if it continues to promote Windows Phone too, and meets its minimum royalty requirements? It is possible, but I really doubt that such clause exists.The decision to go Windows Phone exclusive was purely Nokia’s, and was based on high hopes for Microsoft OS, way too inflated confidence in its own sales force, and belief in ability to “flip a switch” and cram almost anything down consumer throats. After all, back then, even disastrous phones like Nokia N97 sold in millions. And, in late 2010, they managed to ship 5 million smartphones running the flawed Symbian^3 OS, within 3 months after its launch. Why not repeat the feat with Windows Phone next year?But adding the clause that forbids Nokia to even try some other, third party OS? That would be going too far, and may have some serious issues with European competition/anti-trust authorities.