Call Control Client is a general term. It speaks for a suite of software applications that are available with Broadcore. It includes The Telephony Toolbar, Broadcore Unity Client, Call Center Supervisor Client, and Broadcore Receptionist.
You can also use SalesForce.com, ACT!, and other integrated CRM services.
These programs enable a user to use a web-based tool for service invocation and call control.
Call Control Clients provide an alternative to using the handset of the phone. They are not a phone. They are simply a call control. You can dial numbers, use Outlook contacts, View call history lists. You can even use it for transferring. Also, some of the clients allow you to change Broadcore preferences.
For specific details on the Call Control Client you are using, please see that guide.