In telephony, call control refers to the software within a telephone switch that supplies its central function. Call control decodes addressing information and routes telephone calls from one end point to another. It also creates the features that can be used to adapt standard switch operation to the needs of users. Common examples of such features are "Call Waiting", "Call Forward on Busy", and "Do Not Disturb". A telephone handset A touch-tone telephone dial Telephone The telephone or phone (Greek: tele = far away and phone = voice) is a telecommunications device that transmits speech by means of electric signals. ... Computer software (or simply software) refers to one or more computer programs held in the storage of a computer for some purpose. ... central office = Exchange building in the U.S. telephone exchange = Exchange building in the UK, and is also the UK name for a telephone switch, and also has a technical meaning in U.S. telecoms telephone switch is the U.S. term, but is in increasing use in technical UK... A telephone handset A touch-tone telephone dial Telephone This article is about telephone technology. ...

Call control software, because of its central place in the operation of the telephone network, is marked by both its complexity and reliability. Call control systems will typically require many thousands of person years in development. They will contain millions of lines of high level code. However they must and do meet reliability requirements that specify switch down time of only a few minutes in forty years.

The required functionality and reliability of call control is a major challenge for Voice over IP (VoIP) systems. VoIP systems are based on Internet standards and technology which have not previously attempted to satisfy such complex and demanding requirements as those that specify call control. Voice over IP (also called VoIP, IP Telephony, and Internet telephony) is technology enabling routing of voice conversations over the Internet or any other IP network. ...

An alternative name often used is call processing In telecommunication, the term call processing has the following meanings: The sequence of operations performed by a switching system from the acceptance of an incoming call through the final disposition of the call. ...