Use this test mode to perform a measurement, such as BERT, on a known test pattern being sent from the far-end. The far-end signal will be generated by looping back the transmitted signal from this test set. You will use this test set to send a code to automatically loop-up either a CSU or NIU at the far-end. Since a pattern is being sent on the T1 line, service on the T1 will be affected.
Once you have selected this test mode, you can send the loop-up or loop-down code using the buttons on the Control menu. If you are you are using ESF, configure the appropriate ESF Loop Code on the Setup menu.