ITU-T Recommendations

Recommendation ITU-T E.164 provides the number structure and functionality for the eight categories of numbers used for international public telecommunication: Geographic Areas (see clause 3.2.1), Global Services (see networks in clause 3.2.11), Other Global Services (see clause 3.2.19), Global Satellite Services (see clause 3.2.10), Networks (see 3.2.18), Groups of Countries (see clause 3.2.15), resources for Trial (see clause 3.2.22) and Internet of things (IoT)/machine-to-machine (M2M) services/applications (see clause 3.2.17). For each of these categories, it details the components of the numbering structure and the digit analysis required to successfully route calls. Annex A provides additional information on the structure and function of international public telecommunication numbers (hereafter referred to as "international E.164 numbers").