Call number in every telephone (terminal) on one local network is uniquely and to consist of central identification number which that telephone is connected and added customer identification (line) number on that central. Total digits for one costumer number depend on customer density and customer network condition where the customers exist.
CCITT recommended that a total telephone number in every country is 11 digits. In Indonesia, 2 digit used for country code, the number is “62”, 9 digit is for area code and telephone calling number (local number). Because area code in Indonesia to consist of 2 or 3 digit, then total digit maximum for local number in Indonesia is 7, that is only for big cities like Jakarta, Surabaya, Bandung, Medan, and Semarang, that only have 2 digit area code. Example local telephone number (calling number) planned, showed simply on figure 4.5 and 4.6.
Figure 4.5 Numbering on one local central
Figure 4.6 Numbering that involved several local central.
