User`s guide

Dialogic
®
System Release 6.0 PCI for Windows
®
Release Update, Rev 62 — January 30, 2008 215
Dialogic Corporation
the case of hardware other than an IPT Board, this means that media is not enabled at all
until Connect.
Figure 17. H.323 Early Media, SlowStart Mode
1.52.2.3 SIP FastStart Mode (Calling UA Offers SDP)
The SIP protocol does not define distinct “fast start” and “slow start” modes as does
H.323, but the Global Call library uses the same FastStart/SlowStart parameter interface
to allow applications to specify whether the calling UA offers SDP in its INVITE message
or whether it allows the called UA to offer SDP. In the default “FastStart” mode, the calling
endpoint offers SDP and the called UA answers.
Figure 18. SIP Early Media, Calling UA Offers SDP
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
CONNECT
PROGRESS
gc_AcceptCall( )
gc_AnswerCall( )
SETUP(TCS, MSD tunneled)
ALERTING(TCSAck,
MSDAck, MSD, TCS)
FACILITY(OLCAck )
n
FACILITY
(OLCAck , OLC )
nm
FACILITY
(MSDAck, TCSAck, OLC )
m
Unidirectional media
streams are enabled
before each respective
GCEV_EXTENSION
(MEDIAINFO) event
is dispatched.
Unidirectional media
streams are enabled
before each respective
GCEV_EXTENSION
(MEDIAINFO) event
is dispatched.
Pre condition: Both line devices are IDLE. Called party has executed gc_WaitCall().
SlowStart is enabled. Tunneling is enabled.
Post condition: Call is connected.
gc_MakeCall( )
Calling
App
Called
App
IP
CCLib
IP
CCLib
GCEV_ALERTING
GCEV_CONNECTED
GCEV_EXTENSION
(EXTID_MEDIAINFO - TX)
GCEV_EXTENSION
(EXTID_MEDIAINFO - RX)
GCEV_EXTENSION
(EXTID_MEDIAINFO - RX)
GCEV_EXTENSION
(EXTID_MEDIAINFO - TX)
GCEV_DETECTED/OFFERED
GCEV_ANSWERED
GCEV_ACCEPT
gc_AcceptCall( )
gc_AnswerCall( )
Unidirectional media
streams are enabled
before each respective
GCEV_EXTENSION
(MEDIAINFO) event
is dispatched upon
receiving SDP answer.
Unidirectional media
streams are enabled
before each respective
GCEV_EXTENSION
(MEDIAINFO) event
is dispatched after
answering SDP.
INVITE
("m=" , "m=" , ...)
m
n
180 RINGING
("m=" , "m=" , ...)
m
n
200 OK
("m=" , "m=" , ...)
m
n
Pre condition: Both line devices are IDLE. Called party has executed gc_WaitCall().
"FastStart" is enabled.
Post condition: Call is connected.
If the 180 (or 183)
response does not
include SDP answer,
media cannot be
enabled until 200 OK.
ACK
If only one Rx coder is
specified in offer,
streaming is enabled
at time of offer.