I went into the Apple store to replace my, up until yesterday, perfect i4. I started to get the "no sim" display and they swapped it out without question. When it was time to think about jailbreaking I looked at the firmware and was very surprised to see it was 4.0 I figure this means not a a lot of people are returning their i's to have a "refurb" in house still on 4.0. If you returned your i recently which fw was it running? New phone is tits, no issues.