This read-only counter reports how many H.323 calls are currently active and being tracked by the device's H.323 Proxy Filter at this moment, as opposed to the running lifetime total reported by numTotalCalls. An administrator watches this in near-real-time to gauge current call load on the proxy, useful for spotting unusually high concurrent-call counts that might indicate the filter is nearing a capacity limit. For example, if this value spikes far above its typical baseline during a specific hour, that could point to an unusual surge in concurrent VoIP/video calls needing investigation.