ErlangXLS provides Excel AddIns to calculate Call Center staffing requirements based on the widely used formulas of Erlang C und Erlang B. This includes service level, average speed of answer, agent occupation, trunk load, etc. While other providers sell Erlang-based software in expensive products, CC-Logic offers these widely used functions completely free of charge and unlimited. However, CC-Logic recommends using AnswerWIN and AnswerXLS. These functions are much better than Erlang C and Erlang B because unlike Erlang, they take into account abandoned calls.