What is ISDN?

ISDN, which stands for Integrated Services Digital Network, is a set of communication standards developed in the 1980s to transmit voice, data, and video digitally over the traditional circuits of the Public Switched Telephone Network (PSTN). It was a significant technological leap from the older, analog phone system.

For a time, ISDN was a popular choice for businesses needing a reliable digital connection that was faster than dial-up, often used for both voice calls and early internet access. It served as a critical transitional technology, bridging the gap between the analog era and the modern IP-based world.

However, the capabilities of ISDN were quickly surpassed by more efficient, faster, and more flexible technologies like DSL and, later, fiber optic internet.

Today, ISDN is considered obsolete. Telecommunication providers across the globe have either completed or are in the final stages of a process known as the "ISDN Switch-Off," decommissioning these legacy networks entirely. As a result, businesses have migrated to superior IP technologies, primarily Voice over IP (VoIP) and SIP Trunking, which offer far greater functionality, scalability, and cost-effectiveness through modern cloud communication platforms.