Contact centre
Staffing (Erlang C)
The queueing model behind every contact-centre roster. Enter volume, handling time and the service level you have promised; get the agents required to keep it.
A = contacts × AHT ÷ period · SL = 1 − C(n,A) · e^(−(n−A)·T ÷ AHT)
This write-up is too long to fit in a shareable link. Print it or have it emailed instead — both carry the whole thing.
Result
85agents to roster
59 agents handling contacts, plus 30% shrinkage.
- Traffic intensity
- 50 erlangs
- Agents required
- 59
- Rostered
- 85
- Service level achieved
- 94.4%
- Occupancy
- 84.7%
- Average speed of answer
- 3 sec
The occupancy cap set this number, not the service level — at the service-level minimum the team would have been worked past 85%. Two numbers matter. Agents required is what must be on the phone; rostered is what must be employed once breaks, training and absence are added back. Staffing to the first is the most common reason a service level is missed.
Next step
Numbers are the easy half.
Every one of these models is only as good as the operation running behind it. If you would like ours, start with a conversation.