The Automatic Call Distribution (acd software, acd system) distributes incoming calls of a company to employees or agents of the customer service center. The ACD software distributes the calls according to defined rules in order to connect the customer with the best possible employee. Criteria such as skill or language of the agent are taken into account.

The ACD also provides a queue (waiting field) for callers to enter if no agent is available and the call cannot currently be answered. In the queue itself a music on hold is played or an announcement is made about further service offers.

In modern ACD systems, e-mails, faxes, web chats, documents and social media posts are also distributed and can be answered by the Call Center agent.