There are two major cellular network types supported in the US — CDMA and GSM.
Most of the world uses GSM while few counties also supports CDMA (Korea, Japan, Brazil, and Israel).
If your phone happens to be a CDMA phone, it is most likely going to work in the US (roaming rates may still be high though).
If you have a GSM phone, you should check whether it supports the US frequency band (GSM 1900), which is different than the rest of the world, but many phones do support more than one mode.
Advertisement
