It may be that he is closer to a data tower than you are.
http://forum.ppcgeeks.com/showthread.php?t=74422
this is the thread with all the Radio's. Even though you have Alltel you can use any radio on. I'm on Sprint and I use the Telus radio as I heard that was supposed to be better. You can try testing each one out. It isn't supposed to hard reset your phone, but backups are always good precautions to take.