In this mode the Base Station Controller (BSC) is configured as a Remote Line Unit (RLU) with a V5.2 multi-E1 standard interface to the end-office digital switch. The connection between the BSC and the digital switch uses up to 14 E1 fiber, radio, or microwave transmission facilities to accomplish this purpose.

In this RLU configuration, even calls between two TAWA subscribers belonging to the same BSC are switched by the end-office switch.

In this mode the Base Station Controller (BSC) is configured as a Remote Switching Unit (RSU) with an R2-MF multi-E1 interface to the end-office switch. The connection between the BSC and the digital switch also uses up to 14 E1 fiber, radio, or microwave transmission facilities to accomplish this purpose.

In this RSU configuration, the BSC acts as a full-fledged, medium-size Exchange, handling all the traditional functions of a switch such as subscriber administration, billing, and call management.