Filter
Top Products
Dialogic
®
Global Call IP Technology Guide — November 2007 169
Dialogic Corporation
IP-Specific Operations
the connection information from the original INVITE dialog (see Section 4.6.2, “Getting Media
Streaming Status and Connection Information”, on page 155, for details).
Alternatively, the application can modify the properties of the streaming session (for example,
changing to a different codec) at the same time that it retrieves the call from hold. To do this, the
application simply builds a new pair of parameter elements (or a single element for half duplex)
that specify the desired media properties and direction values.
4.8 Setting and Retrieving Q.931 Message IEs
The Dialogic
®
Global Call API supports the setting and retrieving of Information Elements (IEs) in
selected Q.931 messages. The level of support is described in the following topics:
• Enabling Access to Q.931 Message IEs
• Supported Q.931 Message IEs
• Setting Q.931 Message IEs
• Retrieving Q.931 Message IEs
• Common Usage Scenarios Involving Q.931 Message IEs
4.8.1 Enabling Access to Q.931 Message IEs
The ability to set and retrieve Q.931 message IEs is an optional feature that can be enabled or
disabled at the time the gc_Start( ) function is called.
The mandatory INIT_IP_VIRTBOARD( ) function populates the IP_VIRTBOARD structure
with default values. The default value of the h323_msginfo_mask field in the IP_VIRTBOARD
structure disables access to Q.931 message information elements. The default value of the
h323_msginfo_mask field must therefore be overridden with the value
IP_H323_MSGINFO_ENABLE for each ipt board device on which the feature is to be enabled.
The following code snippet provides an example for two virtual boards:
INIT_IPCCLIB_START_DATA(&ipcclibstart, 2, ip_virtboard);
INIT_IP_VIRTBOARD(&ip_virtboard[0]);
INIT_IP_VIRTBOARD(&ip_virtboard[1]);
ip_virtboard[0].h323_msginfo_mask = IP_H323_MSGINFO_ENABLE; /* override Q.931 message default */
ip_virtboard[1].h323_msginfo_mask = IP_H323_MSGINFO_ENABLE; /* override Q.931 message default */
Setting the h323_msginfo_mask field to a value of IP_H323_MSGINFO_ENABLE enables the
setting or retrieving of all supported Q.931 message information elements collectively. Enabling
and disabling access to individual Q.931 message information elements is not supported.
Note: Features that are enabled or configured via the IP_VIRTBOARD structure cannot be disabled or
reconfigured once the library has been started. All items set in these data structures take effect
when the gc_Start( ) function is called and remain in effect until gc_Stop( ) is called when the
application exits.