Call Center and ACD (Automatic Call Distribution)

Call Center functionality is a standard feature of the Asterisk IP-PBX software, and a call center's infrastructure can be easily and economically installed.

A call center consists of IVR, call queues, and agents. IVR (Interactive Voice Response) is the mechanism whereby the system determines the caller's requirements before an agent takes the call. As an example, the following is a typical IVR script: "If you know your party's extension you may dial it now. For sales, press one. For customer care, press two. For technical support, press three." Different IVR scripts can be presented depending on the time of day and/or day of week. The Asterisk PBX system supports customized IVR scripting.

One or more call queues can be allocated. A call queue allows calls to be "stacked" while waiting for an agent to become available. Using the above example, the "Sales", "Customer Care", and "Technical Support" queues would be used to queue calls--the caller's response to the IVR script would determine which call queue to use.

An agent is a person taking calls from one or more call queues. Using the above example, zero, one, or many employees of the technical support department could be logged into the technical support queue. If there are no agents servicing a queue, any calls to that queue go to voice mail. If there are agents servicing the queue, calls placed in the queue will be held until an agent becomes available.

The following diagram is a logical view of the example call center:


The diagram depicts two agents, three queues, and four incoming calls. The call to technical support would go to voice mail since there is not an agent servicing the queue.

There are two methods of servicing a queue. The first method is for agents using a telephone set. As each call arrives, the telephone will ring and the agent will lift the handset to answer the call. The second method is for agents using a headset. As each call arrives, the call will be automatically "dropped" into the agent's headset, and the agent will hear a "gong" sound as each call arrives. An agent's headset typically plugs into a PC running a "soft-phone" program (no telephone set is required).

The following diagram is a physical view of the call center:


The top row depicts persons who may or may not be logged into one or more queues. The bottom row depicts persons whose job it is to take calls and who typically wear a headset.

There are five strategies for distributing calls among available agents:

  • Ring all - ring all available agents until someone answers
  • Round robin - take turns ringing each available agent
  • Least recent - ring the agent which was least recently called by this queue
  • Fewest calls - ring the agent with the fewest completed calls from this queue
  • Random - ring a random agent

An agent typically runs an ERP and/or CRM program on his/her PC. ERP (Enterprise Resource Planning) is an industry term for the broad set of activities supported by multi-module application software that help a manufacturer or other business manage the important parts of its business, including product planning, parts purchasing, maintaining inventories, interacting with suppliers, providing customer service, and tracking orders. CRM (Customer Relationship Management) are the methodologies, software, and Internet capabilities that help a company manage customer relationships in an efficient and organized manner. These applications typically utilize a database server, which is depicted in the diagram above.

Telecom Matters have started a project which integrates the Asterisk PBX software with the Compiere ERP/CRM product. When an incoming call arrives, the PBX will pass the caller ID to Compiere and have it display the client information on the screen. This function is know as "screen pop". The agent will then be able to perform CRM functions without first having to perform database lookups.

A call center using the Asterisk PBX can be very cost effective. The ability to use VoIP protocols from the agent PC's obviates having to purchase expensive telephone sets.