What is an ISDN?

An Integrated Service Digital Network (ISDN) is the original high-speed internet service. It sparked the development of high-speed internet between service providers during the 1990s and, of course, revolutionised internet use. Much like its predecessor, the dial-up internet service, ISDN requires a phone line. Although ISDN set the standard for telephone data service, these days it’s predominantly used for voice.

There are two different types of ISDN. The first is a basic rate ISDN line, also known as a Basic Rate Interface (BRI). This line has two data, or bearer, channels that operate at 64 kbit/sec. Two or more ISDN-BRI lines can be combined to yield speeds of 256 kbit/sec. Combining these lines is common for video conferencing use or transmitting data at higher speeds.

The second type of ISDN line is called a primary rate line, or Primary Rate Interface (PRI). This line has 23 bearer channels and a total speed of 1,544 kbit/sec. It is used mostly for telephone communication rather than data transmission, particularly within companies that have large, private telephone exchange systems operating inside their business.

As technology improved over the last decade and the focus turned to Voice over IP, a new version of ISDN called ISDN over IP was introduced. ISDN over IP is our real world alternative to traditional ISDN solutions and is delivered entirely over an IP network. It allows you to connect your existing analogue, digital, or IP PBX system to most carrier networks. This lets you enjoy all the benefits of ISDN without replacing your PBX or sacrificing the quality of traditional ISDN services.