What Is an Integrated Services Digital Network?
An integrated services digital network (ISDN) is a network that uses existing copper wiring to carry digital signals. ISDNs can transmit voice traffic as well as data packets. These networks are based on a dual channel architecture, with a “B” or bearer channel and a “D” or delta channel. The “B” channel is used for voice, data, multimedia, and video calls, and operates at 64 kbps. “B” channels can be pooled together for applications that require higher bandwidth. The “D” channel, which may be 16 or 64 kbps, is mostly used by switching equipment to allow communication between the in the integrated services digital network and the user’s site. These channels are available in different interfaces. The basic rate interface (BRI) is the most common interface used by people for Internet connections. An ISDN BRI has two “B” channels and a single 16 kbps “D” channel running over a single copper phone line, earning it the name “2B+D.” A BRI can support two voice, fax, or data conversations and
