AUTOMATIC CALL DISTRIBUTOR (ACD)
In telephony, an Automatic Call Distributor (ACD) is a device that distributes incoming calls to a specific group of terminals that agents use. It is often part of a computer telephony integration system.
ACD systems are quite often found in companies who handle a lot of incoming phone calls and where the caller has no specific need to talk to a certain person, but wants to talk to a person who is able to talk to him at the earliest opportunity.
Routing incoming calls is the task of the ACD system. The system consists of hardware for the terminals and switches, phonelines, and software for the routing strategy. The routing strategy is a rule based 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 or ANI is used, more often a simple IVR is used to just ask for the reason. ACD servers can cost anywhere between a few thousand dollars to close to millions of dollars for a very large call center handling thousands of calls per day.
Originally, the ACD function used to be internal to the PBX of the company. However, due to the closed nature of these systems, they lacked flexibility. A system was then designed to enable common computing devices, such as server PC's, to take the routing decisions. For this, generally the PBX would issue information about incoming calls to this external system and receive a direction of the call in response.
An additional function for these external routing applications is to enable CTI. This allows improved efficiency for call center agents because they are offered phone calls with relevant data at the same time on their PC.
A common protocol to achieve this is CSTA, however, almost each PBX vendor has its own taste of CSTA, and CSTA is quite hard to program because of its complex nature. Various vendors have developed intermediate software that hide these complexities and offer programmers a short time to market for their application.
Also, these protocols enable call centers consisting of PBX'es from multiple vendors to be treated as one virtual contact center. All real-time and historical statistical information can then be shared amongst call center sites
