1. A method of routing traffic between an originator and a destination through a switching centers, from local users or from other switching centers, whereby a continuous electrical circuit is established and maintained between the calling and called stations until it is released by one of those stations.
The method of establishing the connection and monitoring its progress and availability may utilise a separate control channel as in the case of ISDN or not as in the case of the public switched telephone network.
2. A process that, on demand, connects two or more data terminal equipments (DTEs) and permits the exclusive use of a data circuit between them until the connection is released.
Circuit switching has been used extensively for the public switched telephone network.
Roughly the opposite of packet switching.
Source: from Federal Standard 1037C and from MIL-STD-188