I have an unlocked iphone 3g running os 3.0, i put in the apn settings and enabled 3g in the network settings. but i still dont get a 3g sign at the signal. anyone might be able to help?

im using maxis. well last time i applied for the rm99 plan but my iphone rosak so i cut the plan off.. now how do i get the signal back? i havent return to maxis to reaplly the plan, since im using postpaid... so does that mean i have to acivate the plan again?

Everything was okay after I input the correct settings for MMS using the iphone configuration thing, but now I suddenly cannot recieve and send MMSes.. Anyone have a clue why can this happen? I never did anything to the profile, I never did anything to the settings =(