The nine world zones are generally organized geographically, with exceptions for political and historical alignment. Zone 1 uses an integrated numbering plan; four digits (1xxx) determine the area served in Canada, the United States and its territories, and much of the Caribbean. Zone 2 uses two 2-digit codes (20, 27) and eight sets of 3-digit codes (21x–26x, 28x, 29x), mostly to serve Africa, but also Aruba, Faroe Islands, Greenland and British Indian Ocean Territory. Zones 3 and 4 use sixteen 2-digit codes (30–34, 36, 39–41, 43–49) and four sets of 3-digit codes (35x, 37x, 38x, 42x) to serve Europe. Zone 5 uses eight 2-digit codes (51–58) and two sets of 3-digit codes (50x, 59x) to serve South and Central America. Zone 6 uses seven 2-digit codes (60–66) and three sets of 3-digit codes (67x–69x) to serve Southeast Asia and Oceania. Zone 7 uses an integrated numbering plan; two digits (7x) determine the area served: Russia or Kazakhstan. Zone 8 uses four 2-digit codes (81, 82, 84, 86) and four sets of 3-digit codes (80x, 85x, 87x, 88x) to serve East Asia, South Asia and special services. 83x and 89x are unallocated. Zone 9 uses seven 2-digit codes (90–95, 98) and three sets of 3-digit codes (96x, 97x, 99x) to serve the Middle East, West Asia, Central Asia, parts of South Asia and Eastern Europe.
The nine world zones are generally organized geographically, with exceptions for political and historical alignment. Zone 1 uses an integrated numbering plan; four digits (1xxx) determine the area served in Canada, the United States and its territories, and much of the Caribbean. Zone 2 uses two 2-digit codes (20, 27) and eight sets of 3-digit codes (21x–26x, 28x, 29x), mostly to serve Africa, but also Aruba, Faroe Islands, Greenland and British Indian Ocean Territory. Zones 3 and 4 use sixteen 2-digit codes (30–34, 36, 39–41, 43–49) and four sets of 3-digit codes (35x, 37x, 38x, 42x) to serve Europe. Zone 5 uses eight 2-digit codes (51–58) and two sets of 3-digit codes (50x, 59x) to serve South and Central America. Zone 6 uses seven 2-digit codes (60–66) and three sets of 3-digit codes (67x–69x) to serve Southeast Asia and Oceania. Zone 7 uses an integrated numbering plan; two digits (7x) determine the area served: Russia or Kazakhstan. Zone 8 uses four 2-digit codes (81, 82, 84, 86) and four sets of 3-digit codes (80x, 85x, 87x, 88x) to serve East Asia, South Asia and special services. 83x and 89x are unallocated. Zone 9 uses seven 2-digit codes (90–95, 98) and three sets of 3-digit codes (96x, 97x, 99x) to serve the Middle East, West Asia, Central Asia, parts of South Asia and Eastern Europe.