In telecommunications, busy-hour call attempts (BHCA) is a teletraffic engineering measurement used to evaluate and plan capacity for telephone networks.
BHCA is not to be confused with busy hour call completion (BHCC) which measures the throughput capacity of the network.
If a bottleneck in the network exists with a capacity lower than the estimated BHCA, then congestion will occur resulting in many failed calls and customer dissatisfaction.
As an example, a telephone exchange with a capacity of one million BHCA is estimated to handle 250,000 subscribers.
The overall calculation is more complex however, and involves accounting for available circuits, desired blocking rates, and Erlang capacity allocated to each subscriber.