This test checks the integrity of a circuit-switched B-channel connection between the switch and the endpoint.

The endpoint is put in the maintenance busy state to prevent the switch from entering calls to the endpoint during the test. An application message containing a loopback activate request for the appropriate B-channel is sent to the endpoint. The endpoint responds with a loopback activated response. The switch then sends data to the endpoint over the B-channel under test. Since the B-channel is looped back at the endpoint, maintenance should receive the data that it sent. If no data is detected, the test fails. The switch then releases the endpoint so that it is available to terminate calls.

This test is not executed for ASAI adjuncts because adjuncts do not support MIMs upon which this test is based. This test is run on BRI-SET, Various Adjuncts.