Factory unlocked Iphone 4 got locked

Hello

I recently bought an phone 4 from a guy that told my that he bought the phone factory unlocked from Portugal. I tried to update the phone to 4.2 with Itunes the phone got locked! I had Cydia and Installer on my phone. Could it be that Apple locked my phone for that reason or do you think that the phone was never factory unlocked in the first place?

Thanks.

It sounds like you're confusing "unlocked, locked" with "jail broken". Your phone is still unlocked but when you updated it with a new iOS from Apple, you lost the "jail break".

If you're using the iPhone here in the US and it's unlocked, it can be used with any carrier that has GMA (AT&T, T-Mobile). All you need is a SIM card.

Also to clarify having owned 2 Factory unlocked iPhones in the past. They will never lock no matter what the phones IMEI number is stored in Apple' servers so when ever you sync,restore or update in iTunes the phone stays unlocked, Regardless of Cydia or any other jailbreak stuff. It sounds like you bought a locked phone that was jailbroken and unlocked via Hack and not by Apple.