Having an issue with data connection on my iphone 4. It was working fine last night but today it just keeps timing out. I check the data settings and all seems ok.
Try re-activating the settings again or turn the phone off, take the sim out and then replace it all and put it back on again.. or maybe the signal where you are at the moment is weak
I'm not familiar with iphone but see if there's anything in this thread for you: http://community.giffgaff.com/t5/Learn-giffgaff-Top-Tips/giffgaffer-s-guide-to-iPhone-4/td-p/52685