Call Center Glossary of Terms

Automatic Call Distributor

The specialized telephone system used in incoming call centers. It is a programmable device that automatically answers calls, queues calls, distributes calls to agents, plays delay announcements to callers and provides real-time and historical reports on these activities. May be a stand-alone system, or ACD capability built into a CO, network or PBX.

Automatic Call Sequencer

A simple system that is less sophisticated than an ACD, but provides some ACD-like functionality.

Automatic Number Identification

A telephone network feature that passes the number of the phone the caller is using to the call center, real-time. ANI may arrive over the D channel of an ISDN PRI circuit (out of band signaling), or before the first ring on a single line (inband signaling). ANI is delivered from long distance companies. Caller ID is the local phone company version of ANI, and is delivered inband. ANI is a North American term, and Calling Line Identification (CLI) is an alternative term used elsewhere.

Auxiliary Work State

An agent work state that is typically not associated with handling telephone calls. When agents are in an auxiliary mode, they will not receive inbound calls.


See Adherence to Schedule.

Available State

Agents who are signed on to the ACD and waiting for calls to arrive.

Available Time

The total time that an agent or agent group waited for calls to arrive, for a given time period.

Average Delay

See Average Speed of Answer.

Average Delay of Delayed Calls

The average delay of calls that are delayed. It is the total Delay for all calls divided by the number of calls that had to wait in queue. See Average Speed of Answer.

Average Handle Time

The sum of Average Talk Time and Average After-Call Work for a specified time period.

Average Holding Time on Trunks

The average time inbound transactions occupy the trunks. It is: (Talk Time + Delay Time)/Calls Received. AHT is also an acronym for Average Handling Time, which has a different meaning.

Average Number of Agents

The average number of agents logged into a group for a specified time period.

Average Speed of Answer

Also called Average Delay. The average delay of all calls. It is total Delay divided by total number of calls. See Average Delay of Delayed Calls.

Average Time to Abandonment

The average time that callers wait in queue before abandoning. The calculation considers only the calls that abandon.

Base Staff

Also called Seated Agents. The minimum number of agents required to achieve service level and response time objectives for given period of time. Seated agent calculations assume that agents will be in their seats for the entire period of time. Therefore, schedules need to add in extra people to accommodate breaks, absenteeism and other factors that will keep agents from the phones. See Rostered Staff Factor.

Basic Rate Interface

One of two basic levels of ISDN service. A BRI line provides two bearer channels for voice and data and one channel for signaling (commonly expressed as 2B+D). See Primary Rate Interface (PRI) and Integrated Services Digital Network.

Beep Tone

An audible notification that a call has arrived (also called Zip Tone). Beep tone can also refer to the audible notification that a call is being monitored.


Historically, a term referred to as a standardized task to test the capabilities of devices against each other. In quality terms, benchmarking is comparing products, services and processes with those of other organizations, to identify new ideas and improvement opportunities.

Best in Class

A benchmarking term to identify organizations that outperform all others in a specified category.


Callers blocked from entering a queue. See Blocked Call.


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