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Global Call IP Technology Guide — November 2007 365
Dialogic Corporation
Third Party Call Control (3PCC) Operations and Multimedia Support
5.4.4.2 Unsuccessfully Modifying the Coder
Figure 75 shows a message sequence diagram for an unsuccessful attempt at modifying the coder
of an active dialog:
Figure 75. Unsuccessfully Modifying the Coder
IPML
Library A
Application A
Global Call
Library A
(IPCCLIB)
Application B
Global Call
Library B
(IPCCLIB)
IPML
Library B
gc_MakeCall
SDP Offer 1
GCEV_DIALING
ipm_StartMedia
(RCV_ONLY)
INVITE
SDP Offer 1
GCEV_OFFERED
SDP Offer 1
IPMEV_START_MEDIA
RTP
IPMEV_START_MEDIA
180 Ringing
SDP Answer 1
ipm_ModifyMedia
(TxRx)
RTP
IPMEV_MODIFY
_MEDIA
200 OK
SDP Answer 1
GCEV_ANSWERED
GCEV_SIP_ACK
gc_SipAck
ACK
GCEV_REQ
_MODIFY_CALL
SDP Offer 2
re-INVITE
SDP Offer 2
415 - Media Not Supported
SDP added by the application
in a provisional response will be
automatically included in
the dialog's final response.
Duplicate SDPs will not be
delivered to the application.
GCEV_ACCEPT
GCEV_ALERTING
SDP Answer 1
gc_AnswerCall
GCEV_SIP_ACK_OK
GCEV_MODIFY
_CALL_REJ
ACK
GCEV_REJECT
_MODIFY_CALL
GCEV_SIP_ACK
SIP ACK is automatically
generated by Global Call
for INVITE and
re-INVITE failures.
Per RFC 3264, a stream that is
rejected must not media stream packets.
It is assumed that the original stream
remains intact because
the modification was rejected.
GCEV_CONNECTED
GCEV_SIP_200OK
gc_RejectModifyCall
gc_ReqModifyCall
SDP Offer 2
ipm_StartMedia(TxRx)
gc_AcceptCall
gc_SetUserInfo
SDP Answer 1