Help needed calculating staffing levels

Hi, Can anyone point me in the right direction?

I need to work out how many people are needed to answer 99% of calls to a busy 24 hour line.

I think I need to use an Erlang C Calculator, and I know the number of calls coming in, the average legnth etc etc.

Can someone point me in the direction of somewhere online I can put this information in and get an answer for each hour of the day? I need to know staffing levels for a 1 week period.

Thanks

Louise