Do I need a foreign sim? I don't have one at the moment... Will deactivating with SAM and then connecting to iTunes with my AT&T sim in the phone still allow this to work?You do not have to update. Put in the foreign SIM then connect to iTunes. Or if jail broken, run SAM utili, deactivate iPhone then connect to iTunes. iTunes contacts the activation server and unlocks.
I guess in other words I'm asking whether the foreign sim is a 'check' of sorts, or an actual requirement to get the phone unlocked.