Differences between factory-unlocked and illegally-unlocked iPhone 4G?

An iPhone which has been jailbroken and unlocked would void the Apple warranty. Most of the unlocks which require jailbreak are temporary unlocking methods. So the device may get re locked on future iOS updates. Whereas a Factory unlocked iPhone has Apple warranty and it wont get relocked on future iOs updates. If you want to get an iPhone at low cost, you can get any network locked device from online and use it with the same network. network locked devices are lower in cost when compare with unlocked devices. If you want to use it with all GSM SIM cards, you can unlock it using any permanent unlocking method. For example, you can visit SimpleUnlocking.com and get the remote unlocking service. This method of unlocking is safe, simple, affordable, quick and permanent. It doesn't require a jailbreak too. So you need not worry about void warranty.