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Global Call IP Technology Guide — November 2007 461
Dialogic Corporation
A network device that is opened in multi-protocol mode defaults to IP_PROTOCOL_H323 if the
protocol is not explicitly set in the makecall block.
Note: Applications should not use the gc_SetUserInfo( ) function to set the IP protocol.
When making calls on devices that support only one protocol, it is not necessary to include an
IPSET_PROTOCOL element in the makecall block. If the application tries to include an
IPSET_PROTOCOL element in the makecall block that conflicts with the protocol supported by
the device, the application receives an error.
When using SIP, if the remote side does not send a final response to an outgoing INVITE (sent by
the call control library) within 64 seconds, the gc_MakeCall( ) function times out and the library
generates a GCEV_DISCONNECTED event to the application. If the application attempts to drop
the call before the 64 second timeout is reached, the library’s behavior depends on whether a
provisional response was received. If no provisional response was received before the application
cancels the call, the library cleans up the call immediately. But if a provisional response was
received before the application attempts to cancel the call, the library sends a CANCEL to the
remote side and generates a GCEV_DROPCALL event to the application after it receives a 200OK
response to the CANCEL and a 487RequestTerminated response to the original INVITE, or when a
further 32 second timeout expires.
8.3.17.1 Configurable Call Parameters
Call parameters can be specified when using the gc_MakeCall( ) function. The parameters values
specified are only valid for the duration of the current call. At the end of the current call, the default
parameter values for the specific line device override these parameter values. The makecallp
parameter of the gc_MakeCall( ) function is a pointer to the GC_MAKECALL_BLK structure.
The GC_MAKECALL_BLK structure has a gclib field that points to a
GCLIB_MAKECALL_BLK structure. The ext_datap field within the GCLIB_MAKECALL_BLK
structure points to a GC_PARM_BLK structure with a list of the parameters to be set as call values.
The parameters that can be specified through the ext_datap pointer depend on the protocol used
(H.323 or SIP) and are described in the following subsections.
Variance for H.323
Table 34 shows the call parameters that can be specified when using gc_MakeCall( ) with H.323.
Table 34. Configurable Call Parameters When Using H.323
Set ID Parameter ID(s) and Data Types
GCSET_CHAN_CAPABILITY IPPARM_LOCAL_CAPABILITY
Data structure, type IP_CAPABILITY. See the reference page for
IP_CAPABILITY on page 543 for more information.
Note: If no transmit/receive coder type is specified, any supported
coder type is accepted.
Notes:
The term “String” implies the normal definition of a character string which can contain letters, numbers, white space, and a null
(for termination).