The application initiates an SCCP connection by invoking SCCPConnectRqst, resulting in the generation of an SCCP connect request message (CR) to the far exchange, as shown in the following illustration:
The connection establishment phase ends when the application receives the SCCPCONNCFM message (far exchange sent connection confirm). If the far end refuses the connection request, the application receives a SCCPRELIND indication instead of a connect confirmation, as shown in the following illustration:
Alternatively, the far exchange can initiate the connection by sending the CR message, resulting in the application receiving an SCCPCONNIND event, as shown in the following illustration:
For an incoming connection, the application invokes SCCPConnectResp to signal to the far end that the connection is accepted. If the application refuses the connection, it calls SCCPReleaseRqst, as shown in the following illustration:
After delivering a SCCPCONNIND event to the application, the SCCP layer on the TX board starts a timer. Timing for the response prevents SCCP layer memory and connection resources from being stranded if the application fails to respond. When an application fails to respond to an incoming connection indication before the application connection response timer expires, the SCCP layer automatically refuses the connection to the originator and notifies the application with a SCCPRELIND event for that connection. The time allowed for the application connection response is configured by the ACR_TIMER configuration parameter. This feature can be disabled by configuring the ACR_TIMER value to 0 (zero).