Yeah I have ALLTEL also with wm6 on my titan and its runs smokin ass fast. My location is Columbia, S.C. i get evdo almost over the whole state.
How to fix your problem....
1)U can call ALLTEL data support and they can check and make sure all your services are on and walk u thru it. or....
2) To do it yourself. your user name is the your number including the area code then the phone number to ya phone @alltel.net
ex.8037777777@alltel.net
Password is alltel or alltel.net I for get which it is. REMBEr to check rember password.
Domain is left blank. Do this and that pesky lil user name and pass are incorrect will never come back.
Happy Surfin Bro