national (significant) number (N(s)N)
The National Significant Number (NSN) is the part of the telephone number thatis followed by the country code. This has a geographical assignment.
The NSN part is specified according to E.164 and consists of 12 to 14 digits for the National Destination Code( NDC), which represents the area code(ONKz), the service code(DKZ) or the network code, and the subscriber number( SN). The number of digits is calculated from the total number of digits for the international number, namely 15, minus the 1 to 3 digits for the country code.