ISDN (Integrated Services Digital Network)

There are two forms of ISDN: PRI and BRI. BRI interface supports a total signaling rate of 144 kbps, which is divided up into two B or bearer channels, which run at 64 kbps, and a D or data channel, which runs at 16 kbps. The bearer channels carry the actual voice, video, or data information, and the D channel is used for signaling. PRI or primary rate interface provides the same throughput as a T1 1. 544 Mbps, has 23 B or bearer channels, which run at 64 kbps, and a D or data channel, which runs at 16 kbps.