If you’re familiar with the erlang formula, then that should be easy.
Let E = traffic in erlang,
N =No. of calls
MHT = mean holding time in minutes (avg call minutes)
Then E = N*MHT/60
To translate erlang into financial terms( aka money), you need to know the no. of calls and the mean holding time for each call. The product of these, multiplied by your tariff per minute gives you your total revenue for that hour.
From the formula above,
N*MHT = 60*E
This gives you revenue for the hour. You can aggregate this to give you revenue per day, week, month, etc.
Note that the no. of calls (N) in this case refers to answered calls. Also, this calculation will give you an approximate figure.