This read-only value reports the accumulated cell delay variation (CDV, i.e., jitter) for this circuit in microseconds, again with 0x00FFFFFF meaning the value is not valid. CDV matters most for real-time and CBR traffic because even if average delay is acceptable, high variation in that delay causes jitter buffer overruns and audible/visible artifacts in voice or video. An admin troubleshooting choppy VoIP quality on a circuit would check cktAccumCDV for an unexpectedly large jitter figure rather than assuming the problem is pure packet loss.