Area codes 303, 720 & 983, Telephone prefix in Denver metropolitan area, Colorado, US
Area codes 303, 720 and 983 are a set of telephone prefixes serving the Denver metropolitan area in Colorado. These numbers cover several counties and municipalities, including central city neighborhoods, suburbs and adjacent areas east of the Rocky Mountains.
The system began in 1947 with area code 303, which covered all of Colorado at the time. Additional prefixes were added over the decades to meet demand for new lines driven by population growth and mobile communication.
The telephone codes support communication networks for Denver's business district, research institutions, technology companies, and residential neighborhoods.
Callers within the region must always dial ten digits, even when both numbers share the same area code. This rule applies to both landline and mobile connections throughout the coverage zone.
Area code 983 was introduced in 2022 as a third overlay layer, with no changes required to existing numbers. This triple overlay is among the more recent solutions within the North American numbering plan.
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