Estimating expected traffic- In the begining

[chintanf]

All,

Am trying to estimate the inbound traffic that a customer care center would generate in its begining phase. We are looking at an application like pinless calling cards. Any fixed formulas to generate the traffic estimate?

Is there any way to forecast numbers based on number of expected users, like x number of agents for y number of customers or a erlang model availble for forecasting?

Thanks,