Outbound vs D.M Effort

I run a Call Center for a Direct Marketing firm, so the majority of our Call Center activity is ‘reacting’ to Customer Calls: taking an order, handling C.S. issues, catalog requests, ect.

I want to set up standards and measures for Upselling, Cross Selling, and otherwise generating additonal revenue for the Call Center.

My concern is how to be able to quantify results and show how much revenue our Mailings generated compared to what our additonal outbound efforts produced. Any ideas?