Work out concurrent call capacity instantly with clear inputs, formula shown and shareable results.
Call capacity is the voice reservation divided by per-call bandwidth. The reservation matters because voice needs a priority queue with a guaranteed share, and Cisco's long-standing guidance is to keep that below about a third of the link so best-effort traffic is not starved. Signalling and RTCP take a further small slice.
Call capacity
voice bandwidth = link x reservation x (1 - signalling overhead); calls = floor(voice bandwidth / per-call bandwidth)
Beyond that, data traffic experiences severe starvation during voice peaks. It is a practical rule rather than a hard limit, but exceeding it needs careful testing.
Critically. Without it, the call beyond capacity is accepted and degrades every existing call rather than being rejected cleanly.