E1 and T1 interfaces

E1 interfaces (also called VE1 interfaces) and T1 interfaces (also called VT1 interfaces) can connect to the PSTN as trunk interfaces. An E1 interface provides 32 timeslots and 2.048 Mbps bandwidth. A T1 interface provides 24 timeslots and 1.544 Mbps bandwidth. ITU-T E1 is used mainly in Europe and China. ANSI T1 is used mainly in America, Canada, and Japan.

E1/T1 voice transmission allows a router to provide more communication channels, which improves router utilization.

Figure 14 shows a typical network for E1/T1 interfaces.