I tried searching the forum but couldn't find any relevant responses. I'm currently in Japan and have a T-Mobile sim and OCN/Docomo sim. I've bent trying to do some research to make sure my phone will work when I return to America. I believe sim free and unlocked mean two different things. Some are saying that sim free means that you will be locked to the first carrier sim you put in. But on the Apple website it seems that you can use any sim. I am fine being locked to Docomo as long as I can use Tmobile when I return. I understand the warranty would only be valid in Japan, and I am okay with that. Here are some resources on the Apple Support forums that seem to say it won't be useable outside Japan. https://discussions.apple.com/thread/6543285 https://discussions.apple.com/thread/6478774 https://discussions.apple.com/thread/6539861 Any experiences or help with this would be great! I really want a 6 plus!