N is the number of servers. Call request queuing is supported wilhin TETRA and Erlang C table is therefore useful for trunking capacity estimation under call queuing strategy. With the Erlang C system. Maximum Offered Load Versus B and N B is in % N/B The Erlang C formula is a mathematical equation for calculating the number of agents (advisors) that you need in a call centre, given the number of calls and the service level that you want to achieve Nokia Networks. a Nokia Networks. An Erlang B