Nokia is shaping up to become a strong contender!
Not bad! Nokia Lumia 920 is solidly the third best selling phone on AT&T. All they need to do is to bring their next flagship to every carrier on earth (like the Samsung galaxy s2, s3) and nokia might have a breakthrough here.
Also, as you can see, HTC's Windows Phone offering actually managed to do pretty decently on T-Mobile. None of their Android offerings actually managed to crack the top 3 at any of the carriers, yet the 8x managed to become the 3rd top selling phone on T-Mobile for 3 months.