5.9. Call Suspend and Resume

Call suspend and resume features are supported using the gc_HoldCall( ) and gc_RetrieveCall( ) functions. A call can be suspended by the application or by the network.

When a call is in the Connected state, the application can issue gc_HoldCall( ) on the CRN of the current call to put the call in the suspended state. The application receives a GCEV_HOLDACK event indicating that the call has entered the suspended state. The call remains in the suspended state until a gc_RetrieveCall( ) is issued on the CRN for the call. The application receives a GCEV_RETRIEVEACK event when this occurs.

If the action of suspending a call is initiated by the network (with an SS7 SUS message), the application receives a GCEV_HOLDCALL event. When the network resumes the call, the application receives a GCEV_RETRIEVECALL event. If the network decides to drop the call or the call remains in the suspended state for too long, the application will not receive the GCEV_RETRIEVECALL event but instead receives a GCEV_DROPCALL event. While a call is in the suspended state, it can be dropped or released by the application.

Notes:

1. The Global Call call state, as returned by gc_GetCallState( ), for a suspended call is GCST_ONHOLD.
2. A suspended call can only be resumed by the side that originally put the call in the suspended state. If a call has been placed in the suspended state by the network, the application cannot resume the call using the gc_RetrieveCall( ) function. The gc_RetrieveCall( ) function will fail if this is attempted. Similarly, if a call has been placed in the suspended state by the application, an SS7 RES message from the network will not resume the call.

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