System or international telephone numbering plan is definition by CCITT E163 recommendation, with explained principles that to be connected with numbering for general telephone network. This numbering system aimed to ensure the allocation of a unique number (digit row) to identification every individual telephone line that connected to worldwide telephone network. In this case, that recommendation is not to regulate individual numbering plan in one country, just allocating place for the amount of digit number that can be used on numbering system in national network each country. With this flexibility, then every national network operator in one country to be able to build a national numbering system it self, that considered optimally for condition or country necessity it self
Three row numbering system that generally adopted by operator in mostly country is that interlaced with call for international connection, toll or trunk, and local connection. To build up a connection on the local connection performed directly using the telephone number customer as an address. To build up a connection on the long connection (trunk) and the international connection, performed with using area code (city) or country code first generally is called prefix code, and then added with destination telephone number customer.
Figure 4.1 International telephone numbering system structures
International prefix: to consist of combination 2 digit number, usually “00” (prefix definition is addition number, as area code or country code, on customer calling number/customer local number)
Country code: to consist of 1 until 3 digits, to represent identification code on one country to build up the international connection.
Number national: to consist of prefix area or code area and customer telephone number. This number concluded by local administration provider.
Generally, international prefix that used in all country in the world is “00”, where as for country code concluded according to CCITT E163/E164 recommendation based on district allotment or zone, show on table 4.2.
Zone Region
1 North America
2 Africa
3/4 Europe
5 South America
6 Far East Asia
7 USSR
8 Far East Asia
9 Middle East & Central Asia
Table 4.2 the world telephone numbering zone
(CCITT E163/E164 recommendation)
Indonesia, Singapore, and Australia are example country that to lie on zone 6, so that code country started with digit “6”. Indonesia code country is “62”.
Example, if costumer from foreign country want to call costumer in Bandung which the telephone number is 5402021, then number that must to dial completely is 00-62-22-5402021, which the number “22” is Bandung area code.
