It depends on the version that you've chosen.
If you've bought a standard 2G MAKERphone, it will work with every carrier that supports 2G GSM connection.
2G will remain available in most countries at least by early 2021 (and by 2025 in Europe).
2G was already shut down in Australia, Japan, Taiwan, Singapore.
If you've opted for a 4G MAKERphone, it will work with all carriers that support 4G (LTE) devices (which is 95% of the carriers today and almost every carrier in North America and Europe).