2.31 vSTP MTP3 Screening

The role of vSTP in the SS7 network is to transport messages between originating and destination signaling points. Gateway services need to perform a certain level of message screening. The message acceptance or rejection in the network is verified by the screening procedure that serves as network's initial security check. The message screening depends on the type of message received by vSTP and the contents of the vSTP screening tables.

In order to verify if a Message Signaling Unit (MSU) is permitted, the mtp screening feature compares the information of the unit attempting to pass the specific requirements of vSTP in the vSTP database. The screening functions are defined by using screening tables referred to as screen sets which contain a set of rules in which the MSU is compared. Each screen set is uniquely identified by a screen set name. MTP screening tables provide screening of MTP messages on the incoming link set.