I want a Gevey SIM for an upcoming UK trip. I plan to get a 3 or Vodaphone PAYG SIM for it. My understanding is you need to activate it via iTunes. The questions are, can I activate in the US the morning I leave? I assume not. If not, can I activate on any iTunes computer in the UK? Will I be forced to sync, or do I just click "never register" and unplug the phone and wait? Upon return to the US, I would take the Gevey SIM out. Would I then need to reactivate my normal AT&T SIM? Are there any caveats/downsides to getting a Gevey Ultra S versus just getting a cheap travel phone? Thanks!