Signalling system network is used for switching of messages pertaining to call handling of the network. All nodes in SS7 network are called signalling points. There are many types of signalling points exist like SCP, OAM centres, exchanges etc.
Signalling points are further divided in two parts:
Signalling end points (SEP).
Signalling transfer point (STP).
Messages from one SEP to another SEP travel through STP. STP does not examine messages, it just route them to next destination.