Buy an unlocked SIM-free iPhone.
All iPhone models are world phones, so you can use them almost anywhere. Whether you are a GSM or CDMA network customer, you can roam internationally on GSM networks in over 200 countries or regions around the world. Availability of LTE data varies in some countries or regions and depends on carrier support for certain LTE radio frequencies. Contact your wireless carrier for more information regarding international roaming policies and rates.
IMPORTANT RESTRICTION FOR iPhone, iPad, APPLE TV, AND HOMEPOD SERVICE.
Apple may restrict warranty service for iPhone, iPad, Apple TV, and HomePod to the country where Apple or its Authorized Distributors originally sold the device.