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Dialogic Corporation
4.25.5 Call Transfer When Using SIP
This section describes specific call transfer procedures when using SIP protocol. For complete SIP-
specific call transfer scenarios see Section 3.3, “Call Transfer Scenarios When Using SIP”, on
page 74. The topics covered here include:
• Enabling GCEV_INVOKE_XFER_ACCEPTED Events
• Invoking an Unattended Call Transfer
• Invoking an Attended Call Transfer
• Processing Asynchronous Call Transfer Events
• Handling a Transfer Request
• Making a Transferred Call
4.25.5.1 Enabling GCEV_INVOKE_XFER_ACCEPTED Events
The following code snippet illustrates how to enable the GCEV_INVOKE_XFER_ACCEPTED
event type, which is optionally used to notify the application at party A that party B has accepted a
transfer request. This event type is disabled by default. This event can be enabled for an individual
line device at any time after the line device is opened. The event is enabled in the party A
(Transferor) application, and need only be enabled if the application wishes to receive the events.
Note that there is no equivalent event in H.450.2.
//enable GCEV_INVOKE_XFER_ACCEPTED event
GC_PARM_BLK *t_pParmBlk = NULL;
long request_id;
gc_util_insert_parm_val(&t_pParmBlk, GCSET_CALLEVENT_MSK, GCACT_ADDMSK,
sizeof(long), GCMSK_INVOKEXFER_ACCEPTED);
gc_SetConfigData(GCTGT_GCLIB_CHAN,ldev,t_pParmBlk, 0, GCUPDATE_IMMEDIATE, &request_id, EV_SYNC);
gc_util_delete_parm_blk(t_pParmBlk);
Disabling the event is done in exactly the same way except that the parameter ID that is set in the
GC_PARM_BLK would be GCACT_SUBMSK instead of GCACT_ADDMSK.
4.25.5.2 Invoking an Unattended Call Transfer
The following code snippet illustrates how to invoke an unattended (blind) transfer on a channel
that is in the connected state. In this example, the Refer-To header field of the REFER message that
is sent is set to “sip:500@192.168.1.10”, while the Referred-By header field is automatically
populated by Global Call.
int Gc_InvokeXfer(int channel)
{
INT32 rc;
GCLIB_MAKECALL_BLK t_gclibmakecallblk;
GC_MAKECALL_BLK t_gcmakecallblk = {0};
char invokeaddr[] = "192.168.1.10"; // party C (TRTSE)
char phonelist[] = "500";