For iPhones that start off locked and are officially unlocked by the carrier, is it simply a policy that those carriers only unlock their own phones, or is there a technical reason this is so? If I'm able to go abroad on vacation and "mistakenly" insist that my locked GSM iPhone bought in the U.S. (on AT&T obviously) was bought on their country on their network, can they simply plug my IMEI into their database and give me an official carrier unlock? I'm guessing that every carrier in every country checks the IMEI and serial number against a database on phones from their network, but is it simply policy to not unlock other carrier's phones or technically impossible? Please do not post comments about unlocks via other means, as there are countless threads on that and that information is easily accessible. This topic of official carrier unlocks on originally-locked phones is uncharted, and I'm be curious if it's possible to get around the policy by insisting that my American iPhone is actually with [insert name of local carrier that does official unlocks in the country of your choosing]. Thanks!