A continuity check (CONTCHK) status indication is delivered to the application when the ISUP layer receives a continuity check request message (CCR) from the far exchange.
When the application receives this indication, it must connect a continuity check loop to the referenced circuit. The application indicates the loop is in place by sending a loopback acknowledgment using ISUPStatusReq.
Note: Continuity checks status indications are not supported in BICC.