I work for a fortune 500 company, and my position is in forecasting and strategies. I have reviewed the various forecasting techniques for call centers and I agree as well as incorporate most of the practices. The problem I have come across is how to calculate an accurate staff required based on the normal parameters (i.e. service level, handle time, etc). I am currently using the Erlang C calculation, but I am not 100% confident with it. Is there any other methodologies anyone has found to be successful?