Provides a single primary rate trunk interfaces or a T1 circuits. The PRI is available as T1, E1 or E1R2MFC depending on the market. T1 trunk cards incorporate an integrated CSU/DSU, eliminating the need for an external unit.
The CSU function allows the trunk to be put in loop-back mode for testing purposes. This can be set manually, using the monitor application, or automatically from a Central Office sending a Line Loop Back (LLB) pattern. The DSU function allows the T1 trunk to be shared between data and voice services.