Yacco is yaacs's account manager. Using it you can manage all data related to CATI operators (anagraphics data, availability, raiting and so on).
It lets you send text to operator's mobile, assigning them a rate (useful if you have thousands operators and want to track how good each of them is), manage their availability and to set some short note about them.
Using yacco you can store operators' bank account data and print their contracts and invoices.
Other specific features are available in yacco, these are spotted out on the docs section.