I have scoured the Apple forums and contacted Orange UK, and cannot find an answer to my question, so here goes:
Basically I recently upgraded my iPhone 4 to an iPhone 5 and would now like to sell the old phone. I will probably do this on eBay, so the purchaser could be from anywhere in the world, on any network. I contacted Orange to initiate the unlock and am awaiting my code. The Orange technician I spoke to told me that I wouldn't even need a SIM in the phone to perform the unlock, though I have since discovered this to be false information. From what I gather, the procedure involves inserting a non-Orange SIM into the iPhone before connecting with iTunes in order to unlock it.
Will the newly unlocked phone instantly lock to this new network? i.e. say I borrow a friend's Vodafone SIM to perform the unlock procedure, will the unlocked phone instantly become a Vodafone UK iPhone?
I want to be able to list the item on eBay as an unlocked iPhone 4, that anyone in the world can purchase and use on their carrier. Having paid £20 for the unlock code, it would be a shame if the phone is instantly locked to the network of the temporary SIM.
Also I've seen widespread stories of people not being able to send text messages on unlocked iPhones, due to some old carrier settings being retained during the unlock process. How can I avoid this potential problem? I just want to provide someone with a fully unlocked iPhone that will work on any network.
(PS: I have already seen this page and it doesn't answer my question: http://support.apple.com/kb/HT5014 )