Table of contents Integrated Services Digital Network Layers Physical Layer Data Link Layer Network Layer Channels ISDN B-Channel ISDN D-Channel ISDN H-Channel Interfaces BRI - Basic Rate Interface U Interface T Interface S Interface R Interface PRI - Primary Rate Interface T1 E1 B-ISDN - Broadband-ISDN Services Bearer Services Teleservices Supplementary Service Devices Network Termination Terminal adapter ISDN Router