I have ATT and bought a brand new Tour. It was never activated on Verizon so I was not able to use data once I had unlocked it.
This is the fixfound from somewhere else)
"If you are using an unlocked phone and have "Activation Required" on your home screen or your phone number displays incorrectly, Dial # # 000000 (Send). In the Menu, change the mobile directory number to your phone number and select save. The device will reboot and activate/display the correct number."