1.7.7. Retrieve the Network Call Reference Value (CRV)

The GCIS_EXID_GETNETCRV extension ID is used to retrieve the network call reference value (CRV) for a specified call reference number (CRN). The CRN is assigned during either the gc_MakeCall( ) function for outbound calls or the gc_WaitCall( ) function for incoming calls. If an invalid host CRN value is passed, for example, the CRN of an inactive call, the gc_Extension( ) function will return a value <0 indicating failure.

Note: The GCIS_EXID_GETNETCRV extension ID can be used to invoke the Two B Channel Transfer (TBCT) feature. The TBCT feature is invoked by sending a FACILITY message to the network containing, among other things, the call reference values (CRVs) of the two calls to be transferred. See Appendix B, "ISDN Call Scenarios" for more information on TBCT.

The following table provides the parameter inputs for the gc_Extension( ) function.

Parameter	Input
target_type	GCTGT_GCLIB_CRN
target_id	call reference number (CRN) of the call
ext_id	GCIS_EXID_GETNETCRV
retblkp	set_id - GCIS_SET_GENERIC
	parm_id - GCIS_PARM_NETCRV
	values - network provided
	value_type - int
mode	EV_SYNC

Note: This extension ID is not supported for the BRI/2 board

Example

 int extGetNetCRV (CRN crn)
{
       GC_PARM_DATAP parm_datap;
       GC_PARM_BLKP parm_blkp = NULL, ret_blkp = NULL;
       unsigned long mode;
       int ret_val = 0;
       GC_INFO  t_Info;
       mode = EV_SYNC;
        ret_val = gc_Extension( GCTGT_GCLIB_CRN, crn,
                     GCIS_EXID_GETNETCRV, parm_blkp, &ret_blkp, mode);
       if ( ret_val )
       {
              ret_val = gc_ErrorInfo(&t_Info);
              if (ret_val == GC_SUCCESS) {
                    printf("gc_ErrorInfo() successfully called\n");
                    PrintGC_INFO(&t_Info);
              } else {
                    printf("gc_ErrorInfo() call failed\n");
              }
       } 
       	  	 gc_util_delete_parm_blk( ret_blkp );
       gc_util_delete_parm_blk( parm_blkp );
       return ret_val;
}

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