Colorado is served by several area codes that reflect its diverse geography and population distribution. The state was initially assigned area code 303 when it was established in 1947, covering much of the populated regions, including Denver and its suburbs. Over the years, as the population grew and telecommunications needs expanded, additional area codes were introduced: area code 720 was added in 1998 as an overlay to 303, and area code 970 was established in 2003 to serve the northern and western parts of the state.
As of the latest estimates, Colorado has a population exceeding 5 million residents, contributing to increasing demand for telecommunications services. The area codes are strategically assigned to manage the growing number of telephone lines associated with both residential and business needs, as well as to accommodate wireless services that require additional numbering resources.
Uniquely, Colorado's mountainous terrain and urban centers necessitate a robust telecommunications infrastructure to ensure connectivity across both densely populated cities and more remote rural areas. The state's area codes play a critical role in maintaining communication across its diverse regions. Furthermore, as the technology landscape evolves, including the rise of mobile and VoIP services, Colorado continues to develop its telecommunications frameworks to address changing consumer needs while ensuring efficient use of its area code assignments.
Arvada (CO)
Aurora (CO)
Boulder (CO)
Brighton (CO)
Broomfield (CO)
Castle Rock (CO)
Castlewood (CO)
Columbine (CO)
Commerce City (CO)
Denver (CO)
Englewood (CO)
Highlands Ranch (CO)
Ken Caryl (CO)
Lafayette (CO)
Lakewood (CO)
Littleton (CO)
Longmont (CO)
Loveland (CO)
Northglenn (CO)
Parker (CO)
Southglenn (CO)
Thornton (CO)
Westminster (CO)
Wheat Ridge (CO)
Colorado Springs (CO)
Pueblo West (CO)
Security-Widefield (CO)
Arvada (CO)
Aurora (CO)
Boulder (CO)
Brighton (CO)
Broomfield (CO)
Castle Rock (CO)
Castlewood (CO)
Columbine (CO)
Commerce City (CO)
Denver (CO)
Englewood (CO)
Highlands Ranch (CO)
Ken Caryl (CO)
Lafayette (CO)
Lakewood (CO)
Littleton (CO)
Longmont (CO)
Loveland (CO)
Northglenn (CO)
Parker (CO)
Southglenn (CO)
Thornton (CO)
Westminster (CO)
Wheat Ridge (CO)
Fort Collins (CO)
Grand Junction (CO)
Greeley (CO)
Loveland (CO)
Colorado has 4 area codes (303, 720, 719, 970). These area codes are split between cities or states, so if you want to call to Colorado, you need to know exactly where you would like to call.
The first 3 digits to call Colorado may vary depending on where you want to call to, being one or the other depending on the region or city. Take a look at our listing above to find out which area code you need.
Calling Colorado from another state in the United States is considered a long-distance call. Here’s how to make the call: First, dial the area code for Colorado. Each state, and sometimes specific cities within a state, has unique area codes. Then, enter the 7-digit phone number of the person or business you’re trying to reach. If you’re calling from a landline, check with your provider, as long-distance charges may apply. However, most mobile carriers in the U.S. offer nationwide calling without additional fees. Alternatively, you can use VoIP or internet-based calling apps, like Skype, Zoom, or WhatsApp, to bypass traditional long-distance charges. The number you want to reach should look like this: 1-(AreaCode)-111-2222.
When making calls within the United States, dialing +1 depends on several factors. On most modern mobile phones, carriers automatically recognize the country code when calling within the U.S., so dialing +1 is usually not required; you can simply enter the area code followed by the phone number, such as 213-555-1234. If you’re using a landline, dialing 1 (the U.S. country code) before the area code and phone number is often necessary for long-distance calls; for example, calling from one state to another may require dialing 1-213-555-1234. When calling the U.S. from another country, dialing +1 is necessary, so a call from abroad would be formatted as +1-213-555-1234. VoIP and internet-based calling platforms, like Skype and WhatsApp, generally handle country codes automatically, making it unnecessary to dial +1 manually for U.S. numbers.
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