Originally Posted by
HotelUser
With HTC phones usually to unlock it you buy an unlock code from eBay, put the foreign SIM card in the phone, and it will ask you for the unlock code.
When you BUY the unlock code from eBay make sure the carrier is the same as the original carrier for the device. They will ask you for the phone's IMEI code, which you can find by dialing *#06#.
After that you can use your new carrier with the phone for calling and SMS. MMS and data (web browsing) wont work until you've reconfigured the APN settings on your device. You can either pay your new carrier to do this for you or you can search around for your carrier's APN settings and do it yourself. Windows Mobile most likely stores this information in an XML file or the registry (yes unfortunately you wont be rid of the Windows registry).