The Adtran OPTI-MX module provides a DS3 or EC1 tributary payload from the OPTI-MX system. The signal is made available through one of the in and out BNC pairs on the OPTI-MX chassis.
Adtran 1184002L6 Data Networking Overview
The OPTI-3 Controller Module provides 3 electrical DS3 drops from a single or redundant OC-3 interface when used with an OPTI-3 chassis.