Erlang C calculator evaluates traffic, delay and number of circuits. With two of these parameters it estimates the third one. Typically it is used to dimension call centers. The number of agents are equal to the circuits. Known the number of calls and the call length you can find out the traffic in erlangs at the traffic units converter option. The average delay is expressed as seconds per CCS (a typical call of 100 seconds), or the percentage of total call length.
a. Circuits: known the traffic and the target of delay probability it calculates the circuits needed (or number of agents).
b. Delay: known the circuits and the traffic it calculates the delay probability and the average call delay.
c. Traffic: known the circuits and the delay probability it calculates the traffic supported.
If traffic not attended immediately do not wait in a queue, but it is abandoned, then you can use the Erlang B calculator.
1. Select the calculator mode (circuits, delay or traffic) depending on the unknown parameters.
2. Enter the two known parameters.
4. Click "=" to evaluate the results; click "C" to clear them; click "M+" to save them or "MR" to restore the saved ones.
If in one hour there are 600 calls with call length of 120 seconds, that is a traffic of 20 erlangs. For a target delay probability of 15% the number of circuits needed are 26. The average delay is 2.5 sec/CCS, so, 1800 total seconds or 3 seconds per call. If circuits are incremented to 30, delay is reduced to 2.5%. Those 30 circuits with 15% of delay could attend a traffic of 23.6 erlangs.
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