Understanding Phone Numbers in Guam

Quick Reference Guide

• Country: Guam
• Country Code: +1 671
• International Prefix: 011
• National Prefix: 1
• Regulatory Body: Federal Communications Commission (FCC)

Overview

Guam, a U.S. territory, follows the North American Numbering Plan (NANP). This guide provides a detailed look at Guam's phone number formats, dialing procedures, and the regulatory framework governing telecommunications.

Number Structure

General Number Structure

• Country Code: +1
• Area Code: 671
• Subscriber Number Length: 7 digits

Detailed Number Formats

Type	Format	Example
Landline	+1 671 NXX XXXX	+1 671 472 1234
Mobile	+1 671 NXX XXXX	+1 671 988 5678
Toll-Free	+1 800 XXX XXXX	+1 800 234 5678
Premium Rate	+1 900 XXX XXXX	+1 900 345 6789

• NXX: Represents the exchange code, where N is any digit from 2-9, and X is any digit from 0-9.

Regular Expressions for Validation

• Landline & Mobile:
  ^\+1\s671\s[2-9][0-9]{2}\s[0-9]{4}$
  

• Toll-Free:
  ^\+1\s800\s[2-9][0-9]{2}\s[0-9]{4}$
  

• Premium Rate:
  ^\+1\s900\s[2-9][0-9]{2}\s[0-9]{4}$
  

Dialing Procedures

Domestic Calls

• Landline to Landline: Dial 1 + 671 + 7-digit subscriber number.
• Landline to Mobile: Dial 1 + 671 + 7-digit subscriber number.
• Mobile to Mobile: Dial 671 + 7-digit subscriber number.

International Calls

• Outgoing: Dial 011 + Country Code + Area Code + Subscriber Number.
• Incoming: Dial +1 671 + 7-digit subscriber number.

Number Portability

Guam supports number portability, allowing users to keep their numbers when switching providers, applicable to both mobile and landline numbers.

Major Telecom Operators

Operator	Service Type	Number Ranges
Guam Telephone Authority (GTA)	Landline & Mobile	671-300 to 671-999
Docomo Pacific	Mobile	671-988 to 671-999
IT&E Guam	Mobile	671-777 to 671-888

ITU-T Recommendations

Guam adheres to ITU-T recommendations under the NANP, including:

• E.164: International public telecommunication numbering plan.
• Q.731: ISDN user-network interface layer 3.

Number Allocation and Management

The FCC manages phone number allocation in Guam, ensuring compliance with NANP standards.

Technical Restrictions and Special Cases

• Golden Numbers: No specific regulations in Guam.
• Number Blocking: Available upon request from telecom operators.

Technical Considerations for Developers

When integrating Guam's phone numbers into software, consider:

• Validation: Use provided regex for number validation.
• Formatting: Maintain consistent international formats.
• Portability: Implement logic for number portability.

Recent Changes to Numbering Plan

There have been no recent changes to Guam's numbering plan since its inclusion in the NANP in 1997.

Conclusion

Understanding Guam's phone number system is crucial for telecom professionals and businesses. By following this guide, you can ensure compliance with regulations and enhance your telecommunications infrastructure.