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Pareto Chart. A bar chart that arranges events in order of frequency. Named after 19th century economist Vilfredo Pareto.

PBX/ACD. A PBX that is equipped with ACD functionality.

Peaked Call Arrival. A surge of traffic beyond random variation. It is a spike within a short period of time.

Peg Count. A simple count of the number of times an event has occurred, like moving a peg on a cribbage board or making notches on a piece of wood.

Percent Allocation. A call routing strategy sometimes used in multi-site call center environments. Calls received in the network are allocated across sites based on user-defined percentages. See Call by Call Routing and Network Inter-flow.

Percent Utilization. See Occupancy.

Phone Time. Also known as Total Sign-In Time. Less specific, but sometimes synonymous terms include Active Hours, Staffed Hours, Productive Hours. The total amount of time spent signed in to the phone system.

Poisson. 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 IDs. When an agent wants to receive ACD calls at their telephone, they first must log into the telephone system. Depending on how the telephone system is programmed, there are two different methods an agent can use to log in. The first method uses a Log In ID. When the agent wants to take ACD calls, they enter a (usually four-digit) number. The Northern telephone system then tracks their telephone activity according to that log in number. The other method uses a Position ID. When the agent wants to take ACD calls, they hit their ACD button twice. The Northern telephone system then tracks their telephone activity according to the position ID of the telephone that they used to log in. The major difference between the two different methods is that log in IDs track the telephone activity of a number (which may appear at different telephone locations) and position IDs track the telephone activity of a particular telephone (regardless of whose using it). If your agents always sit at the same telephones, then the position ID method will track the telephone activity of the agents (because the activity of the telephone is always the same as the activity of the agent). If your agents sometime sit at different telephones, then, in order to track the telephone activity of the agents correctly, the Northern telephone system needs to be configured to use log in IDs.

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 (PRI). 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 (PABX). See Private Branch Exchange.

Private Branch Exchange (PBX). 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.

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