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Global Call IP Technology Guide — November 2007 115
Dialogic Corporation
IP-Specific Operations
For incoming calls, tunneling is enabled by default, but it can be configured on a board device level
(where a board device is a virtual entity that corresponds to a NIC or NIC address; see
Section 2.3.2, “IPT Board Devices”, on page 47). This is done using the gc_SetConfigData( )
function with target ID of the board device and the parameters above specified in the
GC_PARM_BLKP structure associated with the gc_SetConfigData( ) function.
Note: Tunneling for inbound calls can be configured on a board device basis only (using the
gc_SetConfigData( ) function). Tunneling for inbound calls cannot be configured on a per line
device or per call basis (using the gc_SetUserInfo( ) function).
4.2 Fast and Slow Call Setup Modes
The Dialogic
®
Global Call API library allows applications to specify whether they wish to use
signaling techniques that exchange media capabilities as early as possible in the call initiation
process. In general, this “fast start” call setup is preferable to the “slow start” setup for several
reasons:
• fewer network round trips are required to set up a call
• media streaming may be possible earlier in the pre-connection phase (“early media”)
• the local exchange can generate messages when circumstances prevent a connection to the
endpoint
4.2.1 Setting the Call Setup Mode
Note: The selection of fast start vs. slow start mode only applies to the first party call control (1PCC)
operating mode. If the Dialogic
®
Global Call API library is initialized in the third party call control
(3PCC) operating mode, the IPSET_CALLINFO / IPPARM_CONNECTIONMETHOD parameter
that is documented in this section is not supported.
The same Global Call parameter mechanism is used to specify slow start vs. fast start mode for
both the H.323 and SIP protocols, even though the result of the mode selection is quite different in
the different protocols. See Section 4.2.2, “H.323 Fast Start and Slow Start”, on page 116, and
Section 4.2.4, “SIP Call Setup Modes”, on page 118, for protocol-specific details on the connection
modes.
Dialogic
®
Global Call API applications can set either the fast or slow call setup mode as the default
mode for the entire system or for all calls on a given line device, and can also override that default
on a call-by-call basis. If the application takes no action to specify the setup mode, the system
default is fast start mode.
To specify the slow start mode, either for an individual call or as the default mode, the application
inserts the following parameter element in a GC_PARM_BLK:
IPSET_CALLINFO
IPPARM_CONNECTIONMETHOD
• value = IP_CONNECTIONMETHOD_SLOWSTART