First please let me know what kind of call center you are setting up.
Is it domestic or International call center?
In outbound scenario, if you are running a marketing campaign with very high call volume, you need a predictive dialler. If you want quality monitoring of the calls, you need a logger. These are optional elements.
The mandatory requirements are IP enabled PBX (Nortel Meridian PBX are the best), Passport Multiservice access switch at India as well as US. What is your expected call volume? What is your expected hold time?
I can give you the exact cost depending upon your inputs .