Call Center Glossary of Terms

Percent Utilization

See Occupancy.


A formula sometimes used for calculating trunks. Assumes that if callers get busy signals, they keep trying until they successfully get through. Since some callers won't keep retrying, Poisson can overestimate trunks required. See Erlang B and Retrial Tables.

Pooling Principle

The Pooling Principle states: Any movement in the direction of consolidation of resources will result in improved traffic-carrying efficiency. Conversely, any movement away from consolidation of resources will result in reduced traffic-carrying efficiency.

Position Monitoring

See Monitoring.

Post Call Processing

See After-Call Work.

Predictive Dialing

A system that automatically places outbound calls and delivers answered calls to agents. When the dialer detects busy signals, answering machines or ring no answer, it puts the number back in queue.

Primary Rate Interface

One of two levels of ISDN service. In North America, PRI typically provides 23 bearer channels for voice and data and one channel for signaling information (commonly expressed as 23B+D). In Europe, PRI typically provides 30 bearer lines (30B+D). See Basic Rate Interface and Integrated Services Digital Network.

Private Automatic Branch Exchange

See Private Branch Exchange.

Private Branch Exchange

A telephone system located at a customer's site that handles incoming and outgoing calls. ACD software can provide PBXs with ACD functionality. Also called private automatic branch exchange (PABX).

Private Network

A network made up of circuits for the exclusive use of an organization or group of affiliated organizations. Can be regional, national or international in scope and are common in large organizations.


A system of causes.

Profit center

An accounting term that refers to a department or function in the organization that does not generate profit. See Cost center.

Public Switched Network

The public telephone network which provides the capability of interconnecting any home or office with any other.

Quantitative Forecasting

Using statistical techniques to forecast future events. The major categories of quantitative forecasting include Time Series and Explanatory approaches. Time Series techniques use past trends to forecast future events. Explanatory techniques attempt to reveal linkages between two or more variables. See Judgmental Forecasting.


Holds callers until an agent becomes available. Queue can also refer to a line or list of items in a system waiting to be processed (e.g., e-mail messages).

Queue Display

See Readerboard.

Queue Time

See Delay.

Random Call Arrival

The normal, random variation in how incoming calls arrive. See Peaked Call Arrival.


Also called displayboards or wall displays. A visual display, usually mounted on the wall or ceiling, that provides real-time and historical information on queue conditions, agent status and call center performance.

Real-Time Adherence Software

Software that tracks how closely agents conform to their schedules. See Adherence to Schedule.


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