Checking if iPhone 4 is factory unlocked
I am considering buying an iPhone from a person who's selling his, and he claims it to be factory unlocked. I have several reasons to believe this, but I want to be sure.
The first reason is that, although it has Cydia installed, it crashes everytime it starts, so it's not properly installed and the iPhone is not properly jailbroken. Another indication that iPhone is not really jailbroken is that I installed iBooks in it, which you all know that gives an error message when is run in jailbbroken iPhones, and in this iPhone it runs fine.
Since Cydia is not running, I have no way yo check if the iPhone has the ultrasn0w package installed, which would be a clear indication that the iPhone needed an unlock, and therefore is not factory-unlocked. But I checked on the phone's baseband, and it is 04.11.08, which I have searched for in the internet, and ultrasn0w is not capable of unlocking this baseband. But my friend is using the phone with his sim card, which is from a carrier that does not sells iPhones. So this should mean that the iPhone is indeed factory-unlocked.
Am I right?
The problem is I want to buy it and then I will restore it to iOS 5.1 (it's currently in iOS 5.0.1) but I do not want to risk locking it again, if it's not factory unlocked. That's why I want to make sure is factory-unlocked. Are there any other indications that I can check for? Are the indications described above good signs that the phone is factory-unlocked? Thanks in advance for your help.