Integrated Services Digital Network (ISDN) Details

As a global standard for digital data transmission over traditional telecommunications networks, ISDN runs on ordinary copper wires but offers faster data transfers and improved results than analog transmission. While it has been popular for several years, it is to be phased out in specific areas; it remains widely used worldwide. Many legacy services continue to benefit from the system's advantages, such as:

  • multiple digital services possible with the same copper wire;
  • multiple devices and services possible over the same line (for example, fax machines, credit card readers, etc.);
  • digital compatibility with telephone lines; and
  • higher data transfer rate compared to other modems.

Examples of Integrated Services Digital Network

Among the most appreciated features of ISDN is its wide customizability. As long as a host can access ISDN control functions, they can create countless new applications. For example, a typical phone user may decide to save unique settings that control how their calls get managed. They can assign certain ring tones or notification tones for specific people on their list of contacts. They can also set their phones to forward calls from particular contacts to their assistant or play a recorded response when they couldn't or don't want to be disturbed. A caller who would rather not leave a recorded message can be automatically transferred to the receiver's home phone while keeping the home number undisclosed through ISDN.

Another common end-user application of the ISDN concerns data retrieval set to the identity of the caller. A manager of a big company, for instance, may program reminders of deadlines for certain tasks to be performed by specific employees. Each time these workers call, the manager can see detailed information about them, such as points that need to be raised or brought up during the conversation. This ISDN feature can display previous or current orders, delivery schedules, and other related information. You can program even personal reminders for birthdays, anticipated TV shows, names of places to visit, and so on in an ISDN device.

Types of Integrated Services Digital Network

Incompatible with wireless systems, ISDN transmits data over standard telephone lines and follows a telecommunications signaling system. But there are variances in these systems that are crucial to how they function, hence the following ISDN types:

Basic Rate Interface (BRI-ISDN): Basic Rate Interface ISDN is the data access option that Internet users are familiar with. It runs on typical copper telephone lines, with uploads and downloads at a speed of 128 Kbps. In this set-up, two 64 Kbps data channels, known as bearer channels, transmit data packets, while a 16- Kbps channel takes care of control information. Telecom companies often refer to this service as ISDN2, with "2" indicating the system's bi-data channel structure.

Primary Rate Interface (PRI-ISDN): A higher-speed ISDN, Primary Rate Interface can run as fast as 1.544 Mbps to 2.048 Mbps on a particular type of digital transmission carrier system termed E1. A T1 system, on the other hand, uses 23 parallel bearer channels, each one carrying 64 Kbps of traffic. This makes the PRI 32 times faster than BRI. Telecom firms in Europe and Asia usually refer to this service as ISDN30, where "30" represents the 30 bearer channels supported by E1 lines.

Broadband (B-ISDN): While never as widely used as BRI nor PRI, Broadband is the latest and most advanced type of ISDN, whose speed can be scaled to up to hundreds of Mbps. It runs on fiber optic cables and is controlled via ATM (asynchronous transfer mode).