This value holds the Q.931/Q.93b cause code most recently received on this port, meaning it reflects what the far-end switch or endpoint reported as the reason for releasing or rejecting a call, again drawn from codes like user-busy, no-user-response, or normal-call-clr-31. This is the counterpart diagnostic to svcAtmConfigQ93bLastCauseTx and is what you'd check to tell whether call failures on this port are the local switch's doing or the remote party's, which changes whether you troubleshoot local config or escalate to the far-end operator. A run of 'user-busy' (17) values would tell an admin the calls are reaching their destination fine and simply not being answered, not a network fault.