dont bother. when i had my first iphone 4, i started getting the error more and more. i finally got fed up and went to att to get a new SIM card. they replaced it for free, however the NO SIM error occurred a few hours later. sometimes you can fix it by going into airplane mode and back out, other times you need to totally reboot. i finally got fed up and went to apple. they said it was a hardware error and they replaced it, and i had to pay the $150 since i was out of warranty.
btw, ive scoured the internet for hours and read everything about this error. i tried everything from replacing the SIM, to cutting it to putting tape on the sim try. people think the contacts were shorting it out on the tray, others think it was an internal reader error. it wasnt worth the hassle anymore. my replacement phone NEVER had the problem even with the same SIM card. problem must have been with the phone itself.
