Colorado phone numbers follow the North American Numbering Plan (NANP) structure: +1 [Area Code] [7-digit subscriber number]. For example, a Denver number might look like +1 303 123 4567. This format applies to both fixed-line and mobile numbers.

To call Colorado from another country, dial the international access code (011), followed by the US country code (+1), the area code, and the 7-digit subscriber number. So, a call to Denver would look like 011 +1 303 123 4567.

Denver uses two main area codes: 303 and 720. These codes cover the Denver metropolitan area. Other parts of Colorado use different area codes such as 719 and 970.

For local calls within Colorado, simply dial the 3-digit area code followed by the 7-digit subscriber number. For instance, to call someone in Denver, you would dial 303-123-4567 or 720-123-4567.

Number portability allows you to keep your existing phone number even when switching service providers. Both mobile number portability (MNP) and fixed-line number portability are available in Colorado. MNP was implemented nationwide in 2003 and fixed-line portability has been around since 1997.

Toll-free numbers in Colorado follow the format +1 8XX 123 4567, where 8XX represents a toll-free code like 800, 888, 877, etc. These numbers can be called from anywhere in the US without charge to the caller.

The Colorado Public Utilities Commission (CPUC) regulates telecommunications within the state. They manage the numbering plan, oversee number portability, and enforce other telecom regulations.

Colorado adheres to the North American Numbering Plan (NANP) to maintain consistency and interoperability with other countries in North America, including the United States, Canada, and parts of the Caribbean. This standardized system facilitates communication across the region.

You should use the international prefix (011) when making calls to Colorado from outside the United States. This prefix signals that you are placing an international call and connects you to the international gateway.

The emergency number in Colorado, like the rest of the United States, is 911. This number connects you to emergency services such as police, fire, and ambulance.

Yes, you can use regular expressions like `^\+1\s(\d{3})\s(\d{3})\s(\d{4})$` for general Colorado numbers and `^\+1\s(800|888|877|866|855|844|833)\s(\d{3})\s(\d{4})$` for toll-free numbers to validate their format.