Call Release

A call can be released by either party, calling or called.

Abnormal Call Release - Case 1

This scenario depicts a a situation where the peer node fails to acknowledge the REL message sent out by HP OpenCall SS7 ISUP.

As a result, HP OpenCall SS7 ISUP:

First retransmits the REL message every T1, until T5 pops
After T5, HP OpenCall SS7 ISUP A issues a MAINTENANCE_SYSTEM_IND indicating T5_TIMEOUT to application A and initiate the “Circuit Reset after T5” procedure by sending a START_RESET_IND primitive to the application. The procedure is controlled by one timer: T17. A reset message (RSC) is sent out upon receipt of the START_RESET_IND_ACK from application.
On each occurrence of T17, an RSC message is sent out.
A MAINTENANCE_SYSTEM_IND indicating T17_TIMEOUT is issued.
The procedure goes on until a STOP_REQ primitive is received from application A. The STOP primitive stops the reset procedure and brings the circuit back to idle state.
A MAINTENANCE_SYSTEM_IND indicating CRS_STOP is issued.

The abnormal call release procedure described in this scenario is applicable to both inbound and outbound circuits.




	NOTE: RSC Message generation upon time-out is suspended if MTP3 is not available or congested.

Figure 18-2 Abnormal Release - Reset Failed

Abnormal Call Release - Case 2

In this case, an RLC message is eventually received during the reset procedure. As a result, HP OpenCall SS7 ISUP completes the reset sequence and issues a RESET_CONF() primitive. A MAINTENANCE_SYSTEM_IND indicating RLC_AFTER_T17 is issued to the application after RESET_CONF.

Figure 18-3 Abnormal Release - RLC Received at Last

Call Release

Technical documentation

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Abnormal Call Release - Case 1

Abnormal Call Release - Case 2