If you've recently activated your phone and it's not yet able to make phone calls or use the Internet, performing a Profile Update from the device forces the phone to request its device configuration from the network which should get you up and running.
As a result of the variation in the settings from one phone to the next, the following may not perfectly describe where you can locate the Profile Update command on your phone, however, it should get you very close.
On your phone:
Menu > Settings/Tools > Settings > Others > Data > Update Data Profile
Once you've selected "Update Profile," all you need to do is wait until the update completes and then reboot your phone.