One or more MTP congestion (MTPCONGEST) indications are delivered to the application when the ISUP layer receives a congestion indication from the MTP 3 layer. The rangStat member of the status event structure (SiStaEvnt) is populated when MTPCONGEST indications are delivered to the application.
The range value indicates the number of affected circuits minus one. The circuit member of the IsupRcvInfoBlk indicates the first affected circuit. The application must avoid using affected circuits until an MTP stop congestion (MTPSTOPCONGEST) is received.