If I’m going to be living in a foreign country for a few weeks or months, I’ll pick up a local SIM card and buy a pre-paid mobile phone plan, giving me a local phone number and fast internet access in country. The sim card costs about , and I pay about a month for voice, text, and 3GB of 4G data. The sim card is free, and I pay about a month for 14GB of 4G data. Every country will have their own local cell service providers.
I generally like to go with the most popular one — which is easy to find by simply asking locals once you arrive.
This is by far the cheapest option out there, especially for longer-term travel.
Once your phone is unlocked, you can use sim cards & data plans from other companies when you’re traveling. Data speeds are often throttled after a certain amount has been used, or coverage is sparse.