ITU-T E.164 (02/2026)
The international public telecommunication numbering plan
Standard Introduction
ITU-T E.164 (02/2026) is the current international public telecommunication numbering-plan Recommendation. Approved on 13 February 2026 as Edition 7, it supersedes the 2010 edition and defines the structure and routing analysis for eight categories of international numbers.
An international E.164 number contains no more than 15 digits. International access prefixes, national trunk prefixes, display separators and the plus sign are not part of the underlying E.164 digit string. National regulators and numbering authorities remain responsible for assignments and enforceable implementation rules.
Global Number Structure
Defines the structure and routing analysis for international public telecommunication numbers, with a maximum length of 15 digits.
Eight Number Categories
Covers geographic areas, global and other global services, satellite services, networks, groups of countries, trials, and IoT/M2M services and applications.
2026 Operational Baseline
Edition 7 supersedes the 2010 Recommendation and provides the current reference for operators, numbering authorities and systems handling international numbers.
list_alt E.164 Implementation Essentials
- Store the country code and national significant number without national trunk prefixes
- Enforce the 15-digit maximum for international E.164 numbers
- Keep presentation characters separate from the underlying digit string
- Preserve the correct structure for geographic, global, network, satellite and IoT/M2M resources
- Validate routing and digit-analysis rules with the applicable numbering authority
- Track ITU-T assignments, reclamations and national numbering-plan changes
- Test normalization across voice, messaging, identity, billing and fraud-control systems
Who Needs to Comply?
Telecommunication regulators, national numbering authorities, fixed and mobile operators, satellite and global-service providers, IoT/M2M service providers, communications-platform vendors, identity and messaging services, billing teams, and software systems that store, normalize, route or validate international telephone numbers.
Key Requirements
Apply the International Structure
Represent the international number as the country code followed by the category-specific fields and subscriber number. Do not treat an international access prefix or national trunk prefix as part of the E.164 number.
Control Number Length
Enforce the applicable field lengths and the overall maximum of 15 digits. For geographic numbers, the national significant number length is 15 minus the country-code length.
Classify the Numbering Resource
Identify whether a number belongs to a geographic area, global service, other global service, satellite service, network, group of countries, trial, or IoT/M2M category before applying structure and routing rules.
Separate Storage from Presentation
Keep the canonical digit string distinct from display notation, separators, the plus sign, URI syntax and local dialling prefixes, which are governed by presentation or application rules outside E.164.
Govern Assignments and Changes
Use authoritative ITU-T and national numbering records, assign ownership for reference-data updates, and test changes across routing, portability, identity, billing, emergency and fraud systems.
Implementation Roadmap
Inventory number handling
Identify every system, API, file and supplier that captures, stores, displays, validates, routes or enriches telephone numbers. Record the controlling national numbering plan and business owner for each flow.
Define a canonical model
Store the country code and remaining international number digits separately from access prefixes, trunk prefixes and display formatting. Define how extensions and application-specific metadata are handled outside the E.164 value.
Implement validation and normalization
Enforce digit-only structure and the 15-digit ceiling, then validate category and national-plan rules with authoritative reference data. Avoid assuming that every number shorter than 15 digits is assigned or reachable.
Test end-to-end behavior
Test international and domestic input, portability, routing, messaging, identity matching, billing, fraud controls and display output across representative markets and edge cases.
Monitor numbering changes
Assign owners for ITU-T and national numbering updates, assess downstream impact, version reference data and rerun regression tests after assignments, reclamations or plan changes.
Compliance Checklist
checklist Scope and ownership
checklist Canonical data
checklist Validation and operations
Which telephone-number standard answers which question?
Use E.164 for the international number structure, E.123 for human-readable notation, and RFC 3966 when a telephone number is represented as a URI.
| Reference | Primary question | Typical use |
|---|---|---|
| ITU-T E.164 (02/2026) | What digits and fields form an international public telecommunication number? | Numbering plans, routing and canonical data |
| ITU-T E.123 | How should telephone numbers be written and displayed? | Documents, interfaces and contact information |
| RFC 3966 | How is a telephone number represented as a tel URI? | Web links, APIs and application protocols |
| National numbering plan | Which ranges are assigned and how are they dialled locally? | Market-specific validation and operation |
Common Misconceptions
E.164 means adding a plus sign to any local number.
A canonical international number needs the correct country code and national significant number, without the domestic trunk prefix, and must belong to an assigned range.
Every number can be normalized correctly from the digits alone.
A local number may be ambiguous without its market or calling context. Normalization rules need jurisdiction and authoritative numbering-plan data.
The 2010 E.164 edition is still current.
ITU lists the February 2026 Edition 7 as in force and the November 2010 edition as superseded.
Penalties & Enforcement
ITU-T E.164 is a voluntary Recommendation and does not create a direct global fine or certification requirement. National numbering laws, regulator assignments, licence conditions and operator interconnection rules can make correct implementation operationally or legally necessary. Incorrect use can cause failed routing, number collisions, billing errors, fraud-control gaps or loss of assigned numbering resources.
Frequently Asked Questions
What is the current version of ITU-T E.164?
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ITU lists E.164 (02/2026), approved on 13 February 2026, as the in-force Edition 7. The previous November 2010 Recommendation and its amendment are superseded.
How many digits can an E.164 number contain?
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An international E.164 number has a maximum length of 15 decimal digits. The field lengths within that limit depend on the country code and number category.
Is the plus sign part of an E.164 number?
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No. E.164 defines the underlying international number as digits. A plus sign is commonly used in written or application notation to indicate international format, but presentation conventions and URI syntax are handled by other specifications.
Should a national trunk prefix be stored in the E.164 value?
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No. E.164 states that the national trunk prefix is not included in the national significant number and must not be dialled after the destination country code at the international level.
Does a 15-digit string automatically qualify as a valid telephone number?
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No. Length is only one test. The country code, assigned range, number category, national numbering plan, status and operational reachability must also be validated using authoritative current data.
Is E.164 legally mandatory everywhere?
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ITU describes compliance with the Recommendation as voluntary. National laws, regulator assignments, licence conditions and interconnection rules determine enforceable obligations in each market.
Official Documentation
Official PDF for ITU-T E.164 (02/2026)
Official publication or summary for ITU-T E.164 (02/2026)
Official online resource
International Telecommunication Union (ITU) guidance and reference material
Implementation toolkit
Templates, guidance, or companion resources for ITU-T E.164 (02/2026)