This may have been a fairly big CES for Windows Phone, but it looks like Microsoft still has a fair bit of convincing to do in order to bring all the carriers fully on board. That includes Sprint, which does currently have a Windows Phone in its lineup (and is apparently considering more in the "August-September time period"), but remains decidedly unenthusiastic about the platform as a whole. As PCMag reports, Sprint's David Owens said that the carrier is willing to train its reps on Windows Phone, but that Microsoft has to "build the enthusiasm for the product," adding that the "number-one reason the product was returned was the user experienc