According to Microsoft, this restriction is related to system requirements – Windows Phone 7 handsets must include three buttons, and 800×400 pixel multitouch display, a 1GHz processor, an FM radio tuner, a compass, and an accelerometer. No current handset meets those exact requirements.
Not even phones that are very near the requirements are allowed to upgrade – the handset that prompted this news from Microsoft, HTC’s new HD2, has most of the hardware, but sports five buttons instead of the required three. It should also be said that we’re not aware of all of Windows Phone 7′s requirements just yet – some think that a dedicated GPU may be needed to power the OS. Thus, the HD2 is stuck with Windows Mobile 6.5.
It does make sense for Microsoft to keep its new phone operating system confined to new phones – this will lessen the likelihood of incompatibility problems for users and for third-party developers alike. However, it does mean that anyone in the market for a new phone right now will have to bide their time if they want Windows Phone 7, or simply stick with Windows Mobile 6.5.
Those in the latter camp will be happy to know that Microsoft does intend to continue support for Windows Mobile 6.5 after the launch of Windows Phone 7 – after the 6.5.3 update, the operating system will be renamed Windows Phone Classic and will still be supported for an undetermined amount of time. This is similar to Microsoft strategy on the desktop, where older versions of the OS are still updated even after they’re superseded by newer versions.
Microsoft is slated to reveal more about Windows Phone 7 at the MIX developer conference, which is happening from March 15 to March 17.