Do you have WiFi turned on? Also check menu> Settings> Wireless and network> mobile networks and confirm data is enabled. Have you tried Power cycling the device by pulling the battery waiting a minute and trying again. If you are still unable to go to the internet you would want to call Customer service from a different phone, at 1-888-211-4727 So they can reset the the programing on the phone and have it reset it self up.
I'm having this problem with an Epic 4G Touch. Signal strength is either incredibly low or in roaming. Problem has existed for 3 days.
Battery pulls/ factory resets do nothing. Data is turned on. WiFi works. Can not make/recieve calls.
Update PRL and Update Profile does not work, unknown error recieved for both.