Idaho currently utilizes 2 area codes. When first established by AT&T and the Bell System in 1947, 208 covered the entire state of Idaho. The most recently added was 986 in 2017 as an overlay to 208. Today, 208 is the most populated with an estimated 1.6 million of the state's 1.6 million residents.
Sources: North American Numbering Plan Administration (NANPA), telecom providers, and the U.S. Census Bureau.