Originally, PBX was the word for a switch inside a private business (as against one serving the public). PBX means a Private Branch Exchange. Such a "PBX" was typically a manual device, requiring operator assistance to complete a call. Then the PBX went "modern" (i.e. automatic) and no operator was needed any longer to complete outgoing calls. You could dial "9." Thus it became a "PABX." Eventually, all PBXs acquired these automatic features and the "A" became irrelevant. So the PABX is commonly referred to as a PBX, and PABX is an obsolete term. For more information about what they do and where they fit into the call center.

Predictive dialers use complicated software techniques to achieve a careful balance between the number of available agents and the number of calls placed. The pacing algorithm is the mathematical formula the dialer uses to decide how many calls to place at any given moment, taking into account such factors as the average length of calls, the time of day, the accumulated information on the agents' speed, and the hit rate how many calls it can complete versus how many busy and unanswered calls it places. Essentially, the predictive dialer is its pacing algorithm. That is the key component that differentiates one system from another.

The time that an employee is either on duty- handling calls, doing other work, in meetings, etc., or on a paid...