3G bar shows but there really isnt a connection

[amfdfireinside]

Hi all, ive tried searching for a solution to this problem but i think some peopel say it freezes, other say it sticks, and the terminology just keeps changing.
Basically , sometimes, whenever I have my 3g on and I live in athens, ga which has 3g everywhere my iphone will continue to tell me that i have full 3g signal, but really there is NO signal, it wont let me make a call out unless i turn off 3g and turn it back on, or similarly cycle airplane mode on and off.
Other times I wont notice that i didnt have a 3g signal until hours later it magically gets it back again and ill find that i have a couple voicemails magically appear from earlier in the day

Is there any other solution than to just constantly check my 3g access and cycle the airplane mode??

also my phone is jailbroken 2.2 firmware but its been doing this since 2.1