How to enter the SP (Service Provider) unlock code for Windows PocketPC phones
HP, HTC / Cingular 8525, 3125, 2125, T-Mobile SDA, SDA II, XDA, MDA, MDA II, and all Windows Smartphones, Windows Pocket PC Phones:
Insert a SIM card from a different network
Power on the phone
Enter the 8-digit unlock code you received using onscreen keyboard when unlocking a Pocket PC Phone