2.3.1. Sending First Response to an Incoming Call

The gc_CallAck( ) function can be used if the application needs to control the sending of the Setup acknowledge or call Proceeding message to the network, that is, the first response to the incoming call after a GCEV_OFFERED event is received. The type field in the GC_CALLACK_BLK in this context is GCACK_SERVICE_ISDN.

Most applications allow the firmware to handle the first response and therefore this feature is optional. If this feature is required, parameters in the GC_CALLACK_BLK can be set up to handle the following conditions:

• The received setup message contains insufficient destination information. The GC_CALLACK_BLK data structure can be initialized as follows:

        callack.type = GCACK_SERVICE_ISDN; 
        callack.service.isdn.acceptance = CALL_SETUP_ACK; 
        callack.service.isdn.linedev = 0;  

• The received setup message contains all the information necessary to set up the call. The GC_CALLACK_BLK data structure can be initialized as follows:

        callack.type = GCACK_SERVICE_ISDN; 
        callack.service.isdn.acceptance = CALL_PROCEEDING; 
        callack.service.isdn.linedev = 0;  

Notes:

1. When using Springware boards, by default, the SETUP ACK and CALL PROCEEDING messages are automatically sent by the firmware. The gc_SetConfigData( ) function can be use to change the default so that the application controls the sending of the SETUP ACK and CALL PROCEEDING messages (using the GCMSK_SETUP_ACK and GCMSK_PROC_SEND bitmask parameters). See Section 1.9.19, Set ISDN-Specific Event Masks for more information.
2. When using DM3 boards, by default, the application controls the sending of the SETUP ACK and CALL PROCEEDING messages. The gc_SetEvtMask( ) function can be use to change the default so that the firmware automatically sends the SETUP ACK and CALL PROCEEDING messages. See Section 2.30, "gc_SetEvtMsk( )", on page 138 for more information.

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