ISDNtekniikka

ISDNtekniikka, which translates to ISDN technology, refers to a set of digital telecommunication protocols that were developed by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T). ISDN allows for the transmission of voice, data, and signaling over the same network lines, replacing traditional analog telephone lines. It operates by using digital signals throughout the entire transmission path, from sender to receiver.

The core of ISDN is its bearer channels, which carry the actual communication, and its delta channels, which carry control and signaling information. There are two main types of ISDN interfaces: Basic Rate Interface (BRI) and Primary Rate Interface (PRI). BRI typically consists of two 64 kbit/s bearer channels (B channels) and one 16 kbit/s data channel (D channel), often referred to as 2B+D. This made it suitable for small businesses and residential users, offering higher bandwidth than a single analog line and enabling simultaneous voice and data calls.

PRI, on the other hand, is designed for larger organizations and network providers. It offers a greater number of bearer channels, such as 23 B channels and one D channel in North America and Japan (23B+D), or 30 B channels and two D channels in Europe and other regions (30B+2D). The D channel in both BRI and PRI is used for call setup, teardown, and other control functions, providing more advanced features than traditional analog telephony. ISDN offered advantages such as faster call setup, higher data transfer rates, and integrated voice and data services, paving the way for modern broadband technologies.