Do you mean in the sense of a "Predictive Dialing System"?
In that case, it would be used in a telemarketing or collections call center. They can be used for inbound calls as well, such as in a customer service department or other hotline.
One of the systems we use here is the Mosaix PDS. A google search for "Predictive Dialing System" actually leads the page with this page on Avaya about the Mosaix system.
http://www1.avaya.com/enterprise/who...ictivedialing/
I don't know the internals, or specifics of the system, but if you have more questions, please post back and I'll try to answer them.