E164numre

E164numre, or E.164 numbers, refer to the international telephone numbers defined by the ITU-T E.164 numbering plan. They provide a globally unique addressing scheme for the public switched telephone network (PSTN) and for many modern communication systems that rely on telephone addressing, including mobile networks and some VoIP services.

An E.164 number consists of up to 15 digits. It is structured as a country calling code (CC) followed by a national destination code (NDC) and a subscriber number. The country code indicates the country or region; the remaining digits identify the local network and the individual line within that country. In international form, E.164 numbers are written with a leading plus sign, for example, [phone] or [phone].

Administration and routing: The ITU-T defines E.164, while national numbering authorities allocate numbers within their territories and coordinate with other regulators to preserve global uniqueness. When dialed internationally, the number is routed through international gateways via the country code; local dialing may require a trunk prefix or a national format.

Usage and scope: E164numre are the de facto standard for reachability across networks, underpinning directory services, billing, and roaming. They are designed to be technology-neutral in principle; the same number can be used for mobile, fixed-line, or VoIP endpoints, and may be ported or reassigned according to national regulatory practices.

Limitations: E.164 numbers have a maximum length of 15 digits, which constrains future expansion. Some regions use shorter national formats, and emergency services or special numbers may be defined outside the standard numbering plan or use national prefixes not part of E.164.