traffic calculation issue

Hi,

I have the following data relating to IVR traffic for a customer who has 12 port IVR system currently.

Peak hour traffic – 114
Peak day traffic – 944
Peak month traffic – 3794

Yearly traffic – 27000

If I use the erlang minute calculator assuming 12 minutes ( customer data ) a call I get 8 ports.

If I use peak hour traffic calculation I get 33 ports assuming all other variable are fixed.

Could someone help to arrive at the right number of ports for this customer ??

Thanks in advance.

Karthik