Automatic call distributor handles all incoming calls and transfers it to a specific group of terminals. If the number of active calls is less than the number of terminals, the next call will be routed to the terminal that has been in the idle state the longest. If all terminals are busy, the incoming calls are held in a first-in-first-out queue until a terminal becomes available.

An automatic call distributor (ACD) is a device that can be used to distribute incoming calls to a specific group of terminals. ACD is found in every company nowadays, the main purpose of ACD is to receive the call and transfer it to any person at the earliest. There is no specific need to talk to a certain person. The call can be transferred to any available person. Through automatic call distributor facility the customer need not have to wait for such a long time.

The main task of ACD system is to handle incoming calls. ACD comprises of hardware for the terminals and phone lines and software for the routing strategy. The routing strategy is a set of instructions that tells the ACD how calls are handled inside the system. Most of the time this will be a set, that determines the best available employee for a certain incoming call. To help make this match, extra variables are taken into account, most often to find out the reason why the customer is calling. Sometimes the caller’s Caller ID is used; more often a simple IVR is used to just ask for the reason.

ACDs also provide some form of Automatic Customer/Caller Identification (ACIS) such as Direct Inward Dialing (DID), Dialed Number Identification Service (DNIS), or Automatic Number Identification (ANI).