An automated call distribution system, commonly known as automatic call distributor (ACD), is a telephony device that answers and distributes incoming calls to a specific group of terminals or agents within an organization. ACDs direct calls based on parameters that may include the caller's telephone number, the number they dialed, the time of day or a response to an automated voice prompt. Advanced ACD systems may use digital technologies such as Computer telephony integration (CTI), computer-supported telecommunications applications (CSTA) or IVR as input to determine the route to a person or voice announcement that will serve the caller. Experts claim that "the invention of ACD technology made the concept of a call centre possible." Background A Private Branch Exchange (PBX) is a telephone exchange device that acts as a switchboard to route phone calls within an organisation. This technology developed into Automated Call Distribution systems using computer technology to automatically connect incoming calls to recipients based on programmable logic. Although ACDs appeared in the 1950s, one of the first large and separate ACDs was a modified 5XB switch used by the New York Telephone Company in the early 1970s to distribute calls among hundreds of 4-1-1 information operators. Robert Hirvela developed and received a patent for technology that was used to create the Rockwell Galaxy Automatic Call Distributor, which was used by Continental Airlines for more than 20 years. Since then, ACDs have integrated incoming call management and voice messaging software into its capabilities. Application ACD systems route incoming calls to people according to defined rules that may include, for example, the time of day, the day of the week, the geographic location of the caller and the availability of people to respond. The rules should aim to route the call to a person qualified to address the caller's needs. Routing can use caller ID, automatic number identification, interactive voice response or dialed number identification services to determine how calls are handled. ACD systems are often found in offices that handle large volumes of incoming phone calls from callers who have no need to talk to a specific person, but require assistance from any of multiple persons (e.g., customer service representatives or emergency services dispatch centers) at the earliest opportunity. There are several contact routing strategies that can be set up within an algorithm based on a company's needs. Skills-based routing is determined by an operator's knowledge to handle a