I live in the United States, and have an American phone carrier. At the end of this month, I will go to Japan for about a year. I want to register my phone with a Japanese network. However, I do not want to change my SIM card, since I use my current phone number for two factor authentication on countless services.
Here are the options I can think of:
Keep my current (American) carrier, and pay for roaming. Drawback: This is ridiculously expensive, so I only want to do this if there is no other option.
Get a second phone with a Japanese SIM card. I would still have to use roaming with my first phone (i.e., the current, American one), but I would only use it for two factor authentication. I would use the Japanese phone for everything else.
Drawback: It's quite unwieldy to have to carry two phones. If I were only staying for a month, I might just suck it up, but a whole year with two phones seems kind of painful.
Also, I'd have to create a second LINE account for the new phone (since the whole idea is to use the new phone for everything except two factor authentication). I'd have to ask all my friends to add the new account. And then when I leave, I'd have to ask any friends I met in Japan to add the American phone's LINE account. And I would have to repeat this for other platforms beside LINE (pretty much any platform with a "one account per phone" rule).
Switch my two factor authentication to the Japanese SIM card. Drawback: I don't have a comprehensive list of all Internet accounts that I ever opened, so I'm afraid that I might miss some and then get locked out until I return to the US.
All 3 options seem like a major hassle. Am I missing some other option? What do you all do when you go to another country (with different phone carriers) for a somewhat long period of time?