Numbering plan for data networks (X.121)
Numbering plan for public data networks. ITU-T Recommendation X.121 describes the format of data network identification codes (DNIC). All DNICs consist of four digits. The first three digits identify a country; this is the data country code (DCC). The fourth digit enables identification of a network specific in the country.
List of allocated network identification codes (DNIC)
Technical prescriptions
This document is available in German, French and Italian only.