I'll be traveling to Chile with my factory unlocked 5S next month. I've never attempted to use a different company's SIM card before with this phone (or any other). What do I need to do once I get there to use my phone? Is it just as simple as popping out my AT&T nano SIM and putting in one from a local cell company, or are there steps that I need to take separately (such as resetting the phone, etc.)? Also, what tips would you all recommend for settings changes that I should make while overseas and having a (presumably) limited amount of data on a local prepaid plan? Thanks!