Understanding Phone Numbers in Colorado

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

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.