What is the country code for Colorado?

The country code for Colorado, as part of the United States, is +1.

How are phone numbers structured in Colorado?

Phone numbers in Colorado follow the North American Numbering Plan (NANP) structure, consisting of a 3-digit area code followed by a 7-digit subscriber number. The full international format is +1 [Area Code] [Subscriber Number], for example, +1 303 123 4567.

What are the dialing procedures for international calls to Colorado?

To call a number in Colorado from outside the United States, dial the international access code (e.g., 011), followed by the country code for the United States (+1), the Colorado area code, and the 7-digit subscriber number. For example, to call a number in Denver, you would dial 011 +1 303 123 4567.

Is number portability available in Colorado?

Yes, number portability is available in Colorado. Both mobile number portability (MNP) and fixed-line number portability have been implemented, allowing users to retain their phone numbers when switching between service providers.

What are the major area codes used in Colorado?

The major area codes in Colorado include 303/720 for the Denver metropolitan area, 719 for Southern Colorado, and 970 for Northern Colorado.

What is the country code for Colorado phone numbers?

The country code for Colorado phone numbers is +1.

How do I dial a landline number in Colorado from another state in the US?

To dial a landline number in Colorado from another state, use the area code followed by the 7-digit subscriber number. For example, 303-123-4567.

What area codes are used in the Denver metropolitan area?

The Denver metropolitan area uses the 303 and 720 area codes.

Can I keep my Colorado phone number if I switch service providers?

Yes, number portability allows you to retain your phone number when switching between service providers in Colorado.

How do I call a Colorado phone number from outside the United States?

To call a Colorado phone number from outside the United States, dial the international access code, followed by +1, the area code, and the subscriber number. For example, +1 303 123 4567.

What is the format for toll-free numbers in Colorado?

The format for toll-free numbers in Colorado is +1 800 [7 digits]. For example, +1 800 123 4567.

What is the international prefix for dialing out of the United States?

The international prefix for dialing out of the United States is 011.

What is the national prefix for dialing within the United States?

The national prefix for dialing within the United States is 1.

How are phone numbers structured under the North American Numbering Plan in Colorado?

Phone numbers in Colorado are structured with a country code (+1), a 3-digit area code, and a 7-digit subscriber number.

Is there a specific area code for Southern Colorado?

Yes, the area code for Southern Colorado is 719.

What is the emergency number in Colorado?

The emergency number in Colorado is 911.

Can mobile numbers be ported in Colorado?

Yes, mobile number portability has been available in Colorado since 2003.

What regular expression can be used to validate Colorado phone numbers?

The regular expression for validating Colorado phone numbers is `^\+1\s(\d{3})\s(\d{3})\s(\d{4})$`.

What are the area codes for Northern Colorado?

The area code for Northern Colorado is 970.

How do I make an international call from Colorado?

To make an international call from Colorado, dial 011, followed by the country code, area code, and subscriber number of the destination.

What are the types of phone numbers available in Colorado?

In Colorado, the types of phone numbers include fixed-line, mobile, toll-free, and emergency numbers.

United States Phone Numbers: Format, Area Code & Validation Guide

Quick Reference Guide

Country: United States (Colorado)
Country Code: +1
International Prefix: 011
National Prefix: 1

Overview of Colorado Phone Number System

This comprehensive guide delves into the telephone numbering plan in Colorado, USA. It explains the structure of phone numbers, dialing procedures, and number portability. Whether you're a telecom professional, developer, or business, this guide provides essential insights into local number formats.

Number Formats in Colorado

General Number Structure

Colorado adheres to the North American Numbering Plan (NANP). Phone numbers generally follow this structure:

Country Code: +1
Area Code: 3 digits (e.g., 303, 720)
Subscriber Number: 7 digits (e.g., 123-4567)

The full international format for a Colorado number is +1 XXX XXX XXXX.

Detailed Number Formats

Type	Format	Example	Regular Expression
Fixed-Line	+1 [Area Code] [7 digits]	+1 303 123 4567	`^\+1\s(\d{3})\s(\d{3})\s(\d{4})$`
Mobile	+1 [Area Code] [7 digits]	+1 720 123 4567	`^\+1\s(\d{3})\s(\d{3})\s(\d{4})$`
Toll-Free	+1 800 [7 digits]	+1 800 123 4567	`^+1\s(800
Premium Rate	N/A	N/A	N/A
Emergency	911	911	`^911$`

Area Codes in Colorado

303/720: Denver metropolitan area
719: Southern Colorado
970: Northern Colorado

Dialing Procedures

Domestic Calls

Landline to Landline: Dial the area code followed by the 7-digit subscriber number. Example: 303-123-4567.
Landline to Mobile: Dial the area code followed by the 7-digit subscriber number. Example: 720-123-4567.
Mobile to Mobile: Dial the area code followed by the 7-digit subscriber number. Example: 970-123-4567.

International Calls

Outgoing: Dial 011 (international access code), followed by the country code, area code, and subscriber number. Example: 011 +44 20 7946 0958 for a call to London, UK.
Incoming: International callers should dial +1 followed by the Colorado area code and the 7-digit subscriber number. Example: +1 303 123 4567.

Number Portability

Overview

Number portability allows users to retain their phone numbers when switching between service providers. In Colorado, both mobile and fixed-line number portability are supported.

Mobile Number Portability (MNP): Implemented in 2003 across the United States.
Fixed-Line Number Portability: Available since 1997.

Regulatory Body

The Colorado Public Utilities Commission (CPUC) is the regulatory body responsible for telecommunications in Colorado. They oversee the implementation of numbering plans, number portability, and other telecom regulations.

Recent or Upcoming Changes

There have been no significant changes to the numbering plan in Colorado in the past five years. The North American Numbering Plan (NANP) continues to govern the numbering system in the region.

ITU Recommendations

Colorado's numbering system adheres to the ITU-T Recommendation E.164, which defines the international public telecommunication numbering plan.

Number Allocation and Management

Number allocation and management in Colorado are handled under the North American Numbering Plan (NANP). The CPUC, in conjunction with the Federal Communications Commission (FCC), ensures that numbers are allocated efficiently and in accordance with regulatory guidelines.

Technical Considerations

Regular Expressions for Number Validation

Developers working with Colorado phone numbers can use the following regular expressions for validation:

// General Colorado number format
^\+1\s(\d{3})\s(\d{3})\s(\d{4})$

// Toll-Free Numbers
^\+1\s(800|888|877|866|855|844|833)\s(\d{3})\s(\d{4})$

// Emergency Number
^911$

Number Blocking and Restrictions

There are no specific restrictions on number blocking or golden numbers unique to Colorado. Standard NANP rules apply.

Conclusion

Understanding Colorado's phone numbering system is essential for telecom professionals, developers, and businesses operating in or with the state. The information provided here offers a comprehensive guide to the structure, dialing procedures, and regulatory environment of Colorado's telecommunications.

For the most up-to-date information on telecommunications regulations in Colorado, please consult the official website of the Colorado Public Utilities Commission (CPUC).

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