User`s guide

Dialogic
®
System Release 6.0 PCI for Windows
®
Release Update, Rev 62 — January 30, 2008 214
Dialogic Corporation
figure as “FSE”) that can be sent within the messages of the H.225 Setup exchange rather
than using the H.245 messages. (This minimizes the number of round-trip message
exchanges and avoids the latency of H.245 channel establishment.) As a calling endpoint,
the Global Call library enables media after Alerting is received if the called endpoint
supports the fastStart mode. As a called endpoint, the Global Call library enables media in
a fastStart connection after the application calls gc_AcceptCall( ).
If the calling endpoint sets the MediaWaitForConnect element in the Setup message, the
Global Call library does not enable media transmission for a called endpoint until the
Connect message is sent. In the case of hardware other than a Dialogic
®
IPT Board, this
means that media is not enabled at all until Connect.
Figure 16. H.323 Early Media, FastStart Mode
1.52.2.2 H.323 SlowStart Mode
When the application specifies the optional Global Call SlowStart mode, or when one
endpoint does not support H.323 fastStart mode, media transmission cannot begin at
either endpoint until the remote endpoint has sent its Ack to the appropriate
OpenLogicalChannel command.
If the OLCAck that either endpoint receives contains a FlowControlToZero flag parameter
that is true, media transmission is not enabled until a subsequent FlowControl message is
received. In the case of hardware other than a Dialogic
®
IPT Board, this means media is
not enabled at all until the Flow Control message is received.
If the calling endpoint sets the MediaWaitForConnect element in the Setup message, the
called endpoint does not enable media transmission until the Connect message is sent. In
gc_MakeCall( )
Calling
App
Called
App
IP
CCLib
IP
CCLib
GCEV_ALERTING
GCEV_CONNECTED
GCEV_EXTENSION
(EXTID_MEDIAINFO - RX)
GCEV_EXTENSION
(EXTID_MEDIAINFO - TX)
GCEV_EXTENSION
(EXTID_MEDIAINFO - RX)
GCEV_EXTENSION
(EXTID_MEDIAINFO - TX)
GCEV_DETECTED/OFFERED
GCEV_ANSWERED
GCEV_ACCEPT
gc_AcceptCall( )
gc_AnswerCall( )
FACILITY(TCS, MSD)
FACILITY(TCS, MSD,
TCSAck, MSDAck)
FACILITY(TCSAck, MSDAck)
SETUP(fse OLC , OLC ,
OLC , OLC , ...)
Fm Fn
RnRm
PROGRESS(fse with OLC
and OLC )
Ry
Fx
CONNECT(fse with OLC
and OLC )
Ry
Fx
ALERTING(fse with OLC
and OLC )
Ry
Fx
Unidirectional media
streams are enabled
after the ALERTING
is received and before
each respective
GCEV_EXTENSION
(MEDIAINFO) event
is dispatched.
Unidirectional media
streams are enabled
before each respective
GCEV_EXTENSION
(MEDIAINFO) event
is dispatched and
before the ALERTING
response is sent.
Pre condition: Both line devices are IDLE. Called party has executed gc_WaitCall().
FastStart is enabled. Tunneling is enabled.
Post condition: Call is connected.