The connection of networks or circuits in series; that is, the connection of the output of one circuit to the input of another. See Tandem Switch.
A switching arrangement in which the trunk from the calling office is connected to a trunk at the called office through an intermediate point; serves to interconnect central offices when direct interoffice trunks are not available.
Telephone company node / central office classification, containing a switch where all outer and inner area code traffic is handled, in an area code where the handoff for long distance service happens. A central office that carries a call, but only switches the call to the central office where the called customer is served - it does not actually connect the call with the end customer.