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Glossary · Phone system (PBX)

ACD (automatic call distribution)

In one sentence

ACD (automatic call distribution) is the phone system feature that hands calls waiting in a queue to available agents according to a rule you choose, such as round robin, longest idle or skills-based routing.

Also known as : ACD · automatic call distribution · automatic call distributor · call distribution

How ACD distributes calls from a queueA four-step flow. 1: several calls are waiting in the support queue. 2: the ACD checks which agents are logged in and free. 3: it applies the chosen strategy, for example the agent who has been idle longest. 4: the oldest call is offered to that agent; if they don't answer, the ACD moves to the next one.1 · Calls in the queueSupport: 3 callswaiting2 · Available agentsLogged in, not on a call,not on a break3 · Strategye.g. agent idlefor longest4 · Call offeredNo answer? The ACDtries the next agent
ACD doesn't pick at random: it follows a rule you set (round robin, longest idle, skills-based).

What is ACD?

Automatic call distribution is the logic that decides which agent takes which call when several people answer the same number. Without it, calls either ring everyone at once or always hit the first person on the list, and one colleague ends up taking most of the calls.

ACD works hand in hand with the call queue. The queue keeps callers in order of arrival; ACD picks who gets the next one. Together they are the core of any phone-based customer service, from a three-person front desk to a full contact centre.

How it works

ACD tracks every agent’s state: logged in or out, on a call, on a break, or finishing notes after a call (wrap-up). When a call is waiting, it applies the configured strategy:

  • Round robin: each agent gets a call in turn.
  • Longest idle: the call goes to whoever has been free the longest.
  • Fewest calls: to the agent who has taken the fewest calls in the period.
  • Skills-based: by language, product or seniority, often based on the caller’s choice in the IVR.

If the agent doesn’t answer within the set time, ACD moves on to the next one, and can pause the agent automatically so calls stop going to an empty desk. Reports on wait times, abandoned calls and calls per agent then show where staffing needs adjusting.

Example

An e-commerce retailer in Cork selling outdoor gear has five agents, two of whom handle trade accounts. Trade customers call a dedicated number, so their calls enter a separate queue that ACD gives first to the two trade specialists, then to everyone if the wait passes two minutes. Retail calls use longest idle. After a month of reports, the retailer saw that most abandoned calls came on Saturday mornings after a newsletter, and added a part-time agent for those hours.

ACD at Universal Telecom

Our virtual PBX includes call queues and automatic distribution, with reports by queue and by agent. If your team also handles WhatsApp conversations, the WhatsApp page explains how to bring them into the same workspace.

Frequently asked questions

What is the difference between ACD and a ring group?

A ring group simply rings several phones, together or one after another. ACD manages a queue: it holds callers, tracks each agent's status and decides who gets the next call based on a strategy.

What is skills-based routing?

It is an ACD strategy that matches calls to agents with the right skill, such as a language or a product. The skill usually comes from the caller's IVR choice or the number they dialled.

Do small teams need ACD?

As soon as three or more people answer the same number, ACD spreads the work fairly and gives you wait-time and abandoned-call figures. Most cloud phone systems include it.

Related terms

  • Call queue

    A call queue holds incoming callers when every agent is busy and connects them in order of arrival as soon as someone is free, playing music and announcements while they wait.

  • Ring group

    A ring group (or hunt group) rings several extensions for the same number, either all at once or one after another, so the first available colleague can pick up the call.

  • IVR (interactive voice response)

    IVR (interactive voice response) is the automated phone menu that greets callers and routes them based on the keys they press, such as “press 1 for sales, press 2 for support”.

  • Contact centre

    A contact centre is the team, processes and software that handle customer conversations across several channels, such as phone, email, chat and messaging, using shared queues, agents and reporting.

  • CCaaS

    CCaaS (contact centre as a service) is cloud-hosted contact centre software. It receives calls, emails and messages, routes them to agents, manages queues and gives supervisors live dashboards and reports, on a per-agent subscription.

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