An erlang is a dimensionless unit used to measure the total traffic volume on a telecommunications network. One erlang equals one continuous hour of circuit use. For example, sixty calls lasting one minute each equal one erlang. Network engineers use this metric in probability formulas to determine how many lines or channels are needed to prevent blocked calls during peak hours.
The trunk group is carrying 45 erlangs of traffic during the busy hour, so we need to add more capacity to avoid dropped calls.
The Erlang B and Erlang C formulas are the standard mathematical models used to calculate required bandwidth and call center staffing.
Related terms
BHCA
Busy-Hour Call Attempts, a metric used to evaluate the peak processing capacity of a telephone exchange.
Blocked
A state where a call or connection attempt is rejected by the network switch or firewall.
Contention
A state where multiple devices or users attempt to use the same network resource simultaneously.
Hold time
The duration a caller remains in an active queue before an agent answers or the call drops.