The subscription to your wireless plan has nothing to do with the error.
This link contains wvdial setup instructions for almost every type of connection, see if yours is set up correctly:
http://ubuntuforums.org/archive/index.php/t-343989.html
It's a couple of years old now, but info in it is still accurate.
I'm using Network Manager on F11, and have no problems using my Palm/Verizon connection, without the use of wvdial, you might want to try that out if wvdial still doesn't work for you.