Overview
E.164 is a recommendation by the International Telecommunication Union (ITU) that defines the international public telecommunication numbering plan. The recommendation ensures that each country and their respective telecommunication operators follow a standardized method for assigning numbers, facilitating global communication.
Historical Context
The E.164 recommendation was first adopted by the ITU-T (International Telecommunication Union Telecommunication Standardization Sector) in May 1997. It has since become a cornerstone of international telecommunications, allowing for consistent and reliable numbering schemes that can be interpreted and routed worldwide.
Structure and Details
Number Format
An E.164 number typically comprises the following components:
- Country Code (CC): A one to three-digit code that identifies the country or geographic region.
- National Destination Code (NDC): Typically a 1-4 digit code that indicates a specific area or network within the country.
- Subscriber Number (SN): Up to 12 digits identifying the subscriber.
The maximum length of an E.164 number is 15 digits, including the country code.
CC NDC SN
+1 234 5678901
Key Events and Updates
- 1997: Initial adoption of E.164.
- 2005: E.164.1, which covers the procedures for the assignment of global number ranges.
- Recent Revisions: Ongoing updates to accommodate new telecommunication needs and technologies, including VoIP and mobile networks.
Implementation
National and International Dialing
- International: A “+” sign or the international call prefix followed by the E.164 formatted number.
- National: Omission of the country code and possibly the national trunk prefix.
Importance and Applicability
The E.164 standard is vital for:
- Interoperability: Ensures seamless communication across different telecommunication networks worldwide.
- Consistency: Provides a uniform framework for phone number formats.
- Routing: Simplifies call routing processes for operators.
Examples
- United States: +1 800 123 4567
- United Kingdom: +44 20 1234 5678
Considerations
When implementing or adhering to E.164, consider:
- Compliance with Local Regulations: Each country may have specific requirements or additional regulations.
- Length Constraints: Ensure numbers do not exceed 15 digits.
- International Routing Costs: Understand the financial implications of international dialing.
Related Terms
- ITU-T: The sector of ITU responsible for telecommunication standards.
- ISDN: Integrated Services Digital Network, using numbering similar to E.164.
Comparisons
- E.123: A recommendation that covers the notation for national and international telephone numbers.
Interesting Facts
- The ‘+’ sign used in the international format is not dialed but represents the international access code (e.g., 00, 011).
Famous Quotes
“Standards are like toothbrushes. Everyone agrees they are a good idea, but no one wants to use someone else’s.” —Anon.
FAQs
What is the maximum length of an E.164 number?
How do I dial an E.164 number internationally?
References
- ITU-T Recommendation E.164 - The International Public Telecommunication Numbering Plan. Available at: ITU Website
Summary
E.164 is the globally accepted ITU standard for international phone numbering, ensuring interoperability, consistency, and efficient routing in telecommunication systems. It encompasses a structured format with a maximum of 15 digits, aiding global communication across various networks.
By understanding and implementing the E.164 recommendations, telecom operators and users can ensure more reliable and uniform international communication, crucial in our increasingly interconnected world.
graph TD;
A[Subscriber Dialing] --> B[National Destination Code (NDC)];
B --> C[Subscriber Number (SN)];
C --> D[Country Code (CC)];
A --> E[International Call Prefix (+)];
E --> D;
