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Global Call IP Technology Guide — November 2007 157
Dialogic Corporation
IP-Specific Operations
else
{
//only get tx or rx, not both
l_pParmData = gc_util_find_parm(gcParmBlk, IPSET_MEDIA_STATE, IPPARM_RX_CONNECTED);
if(l_pParmData != NULL)
{
memcpy(&l_IPCap, l_pParmData->value_buf, l_pParmData->value_size);
}
}
}
4.6.3 Getting Notification of Underlying Protocol State Changes
The application can receive notification of intermediate protocol signaling state changes for both
H.323 and SIP. The events for this notification must be enabled; see Section 4.6.1, “Enabling and
Disabling Unsolicited Notification Events”, on page 154.
Once these events are enabled, when a protocol state change occurs, the application receives a
GCEV_EXTENSION event. The EXTENSIONEVTBLK structure pointed to by the extevtdatap
pointer within the GCEV_EXTENSION event will contain the following information:
extID
IPEXTID_IPPROTOCOL_STATE
parmblk
A GC_PARM_BLK containing the protocol connection status with the
IPSET_IPPROTOCOL_STATE parameter set ID and one of the following parameter IDs:
• IPPARM_SIGNALING_CONNECTED – The signaling for the call has been established
with the remote endpoint. For example, in H.323, a CONNECT message was received by
the caller or a CONNECTACK message was received by the callee.
• IPPARM_SIGNALING_DISCONNECTED – The signaling for the call has been
terminated with the remote endpoint. For example, in H.323, a RELEASE message was
received by the terminator or a RELEASECOMPLETE message was received by peer.
• IPPARM_CONTROL_CONNECTED – Media control signaling for the call has been
established with the remote endpoint. For example, in H.323, an OpenLogicalChannel
message (for the receive direction) or an OpenLogicalCahnnelAck message (for the
transmit direction) was received.
• IPPARM_CONTROL_DISCONNECTED – Media control signaling for the call has been
terminated. For example, in H.323, an EndSession message was received.
Note: The parameter value field in this GC_PARM_BLK in each case is unused (NULL).
4.7 Modifying an Existing SIP Call via re-INVITE
This section discusses the Dialogic
®
Global Call API implementation of the SIP re-INVITE
method as it applies to first party call control (1PCC). The use of re-INVITE in the context of third
party call control (3PCC) is discussed in Chapter 5, “Third Party Call Control (3PCC) Operations
and Multimedia Support”.
This section includes the following topics:
• Overview of the SIP re-INVITE Method
• Enabling Application Access to re-INVITE Requests