E.164 is an international standard established by the International Telecommunication Union (ITU) that defines the format for telephone numbers. It provides a globally recognized numbering plan for the identification of devices and users in telecommunications networks worldwide.
Key features of E.164 include:
1. Global Uniqueness: E.164 ensures that each telephone number is globally unique. This means that no two devices or users should have the same telephone number worldwide.
2. Format: E.164 specifies the format for telephone numbers, which typically includes a country code, followed by a national destination code, and finally the subscriber number. The country code helps identify the country or region to which the number belongs.
3. Length: The standard allows for telephone numbers of varying lengths, depending on the country or region. However, it generally recommends a maximum length of 15 digits, including the country code.
4. Normalization: E.164 promotes the normalization of telephone numbers, which involves formatting numbers consistently to facilitate interoperability between different telecommunications systems and applications.
5. Usage: E.164-compliant telephone numbers are used in various telecommunications services, including fixed-line telephony, mobile communications, Voice over Internet Protocol (VoIP) services, and SMS messaging.
