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gc_util_insert_parm_val(&parmblkp,
IPSET_MSG_SIP,
IPPARM_MSGTYPE,
sizeof(int),
IP_MSGTYPE_SIP_INFO_FAILED);
// Insert SIP response code
gc_util_insert_parm_val(&parmblkp,
IPSET_MSG_SIP,
IPPARM_MSG_SIP_RESPONSE_CODE,
sizeof(int),
501);
// transmit INFO response message to network
retval = gc_Extension(GCTGT_GCLIB_CRN, crn, IPEXTID_SENDMSG, parmblkp, &retblkp, EV_ASYNC);
4.14 Sending and Receiving SIP OPTIONS Messages
The SIP OPTIONS method provides a means for a SIP User Agent to query the capabilities of
another UA or proxy, either within or outside of a SIP dialog. As an example, a client can use the
OPTIONS method to discover the content types, extensions, methods, codecs, etc. that are
supported by another party without having to “ring” the party by sending an INVITE.
RFC 3261 requires all user agents to support the OPTIONS method. The default behavior of the
Dialogic
®
Global Call API library is to send automatic responses to incoming OPTIONS requests
and not provide facilities for applications to send OPTIONS requests. Optionally, an IPT virtual
board can be configured to enable application access to OPTIONS messages. When access is
enabled, applications can send OPTIONS requests to remote parties and are responsible for
responding to incoming OPTIONS requests.
The following topics describe the Dialogic
®
Global Call API library’s implementation of support
for the OPTIONS method.
• Default OPTIONS Behavior
• Enabling Application Access to OPTIONS Messages
• Sending OPTIONS Requests
• Receiving Responses to OPTIONS Requests
• Receiving OPTIONS Requests
• Responding to OPTIONS Requests
4.14.1 Default OPTIONS Behavior
If the SIP OPTIONS access feature is not enabled when the ipt virtual board device is started, the
SIP stack in the Dialogic
®
Global Call API library responds to incoming OPTIONS requests
automatically, using default information, because all SIP User Agents are required to support the
OPTIONS method. The application has no control over the content of these automatic response
messages, nor can it send OPTIONS requests.