Service switching point
The service switching point (SSP) is a signaling point that originates and terminates traffic in an SS7 network. The functions performed by an SSP include routing and user functions. In the area of routing, the SSP is responsible for determining the destination signaling point for a message and then sending the message towards the destination. The user functions include the recognition of an action requiring signaling network intervention, the creation of the appropriate message for the action, and the processing of received messages.
The SSP can be implemented either as an integral part of the telephone switch or as an adjunct processor to the telephone switch. The latter implementation is more common in networks that are being upgraded to the SS7 network. The accompanying visual depicts such an implementation in which the SSP is tied to the telephone switch via an umbilical that carries call related information. Once the SSP receives the information, it creates the appropriate message and routes this message into the SS7 network.