ITU's 160 anniversary

Connecting the world and beyond

Intelligent networks

  • The Intelligent Network (IN) is a public switched telephone network architecture developed by Bellcore (now Telcordia) and ITU-T. It was created to provide a variety of advanced telephony services such as 800-number translation, local number portability, call forwarding, call screening, and wireless integration. The IN uses the SS7 signaling protocol (a worldwide telephony standard) in which voice or modem data travels through circuit-switched voice switches, while control signals travel over an SS7 packet-switched network. INAP (Intelligent Network Application Part) is an IN protocol used in an SS7 network to query databases for a variety of functions not related to call setup and tear-down. INAP uses ASN.1 for defining message content.
  • The Integrated Services Digital Network (ISDN) and all supplementary telephone services such as reverse charging, closed user groups, and international calling card verification, use ASN.1 and BER.
  • ASN.1 and BER are used in routing 800-number telephone calls.
  • Each call placed on a cellular telephone in North America, Europe, Japan and elsewhere results in the exchange of TCAP protocol messages, which are specified using ASN.1 and encoded using the Basic Encoding Rules (BER) of ASN.1.
  • The Computer Supported Telecommunications Applications (CSTA) standards specify the structure of the messages exchanged between equipment and computing applications in ASN.1 using BER.