Pre-selection is the automatic pre-selection of a connection network operator for handling telephone calls. Each network operator has its own Carrier Identification Code (CIC).
With Carrier Pre-Selection (CPS), this code is preset in the subscriber's local exchange and is used automatically. If the subscriber wishes to use a carrier other than the preset carrier for the connection, the subscriber will dial the appropriate carrier selection code for each connection. This is entered before the local network code. This is referred to as a call-by-call connection.