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Global Call IP Technology Guide — November 2007 345
Dialogic Corporation
Third Party Call Control (3PCC) Operations and Multimedia Support
• Events
• Error Codes
• Global Call Functions Invalid in Third Party Call Control Mode
5.2.2.1 IPCCLIB_START_DATA Data Structure
The IPCCLIB_START_DATA data structure contains a new media_operational_mode field that
determines the Dialogic
®
Global Call API library mode of operation, first party call control mode
(1PCC) or third party call control mode (3PCC).
5.2.2.2 IPSET_SDP Parameter Set Identifier
The IPSET_SDP parameter set ID and parameter IDs described in this section, along with those in
Section 9, “IP-Specific Parameters”, on page 499, are defined in the gcip.h header file. The
IPSET_SDP parameter set ID is only applicable when the Dialogic
®
Global Call API library is
initialized in 3PCC mode. Applications using this parameter ID must use the “extended”
gc_util_..._ex( ) utility functions, which are capable of handling parameter data longer than 255
bytes.
The Dialogic
®
Global Call API 3PCC model transports SDP buffers to and from the host
application through IPSET_SDP parameter set ID parameter blocks that are attached to outbound
SIP messages (generated by Dialogic
®
Global Call API function calls) and inbound Dialogic
®
Global Call API events.
Notes: 1. The SDP offer/answer should be sent only one time during a transaction. Multiple attempts to
send SDP content during a transaction will result in an error.
2. The SDP offer/answer protocol is strictly enforced. If the application receives an SDP offer
within a Dialogic
®
Global Call API event, the application must respond with an SDP answer.
The SDP answer is included as part of the Dialogic
®
Global Call API function call that
completes the SIP transaction. For complete information about the offer/answer protocol with
SDP, refer to the Internet Engineering Task Force (IETF) document RFC 3264 - An Offer/Answer
Model with Session Description Protocol (SDP), which is available at
http://ietf.org/rfc/rfc3264.txt.
Table 20 shows the parameter IDs in the IPSET_SDP parameter set. The SDP content string must
adhere to the following:
• consist of an array of variable length records of the form <type>=<value>
• each record must contain an array of ISO-10646 characters in UTF-8 encoding
• a record’s content must not include 0x00, 0x0a or 0x0d characters
• each record must be terminated with a <CR><LF> (0x0D0A)
• maximum SDP content length is determined by IP_CFG_PARM_DATA_MAXLEN symbolic
define
Sample SDP content is shown below: