HP-UX C SIP Stack Programmer's Guide (Novembery 2007)

6 HP-UX C SIP Stack Programmer’s Guide
Messages
Possible body types include:
 Multipurpose Internet Mail Extensions (MIME)
 Others—to be defined in the IETF and in specific
implementations
MESSAGE SAMPLES The following samples show the message exchange between two User Agents
for the purpose of setting up a voice call. SIP user [e-mail] invites SIP
user [e-mail] to a call for the purpose of discussing lunch. Alice sends
an INVITE request containing a body. Bob replies with a 200 OK response also
containing a body.
R
EQUEST MESSAGE
Table 1-3 Request Message Samples
Request Message Line Description
INVITE sip:[e-mail] SIP/2.0 Request line: Method type, Request-
URI (SIP address of called party), SIP
version.
Via: SIP/2.0/UDP
172.20.1.1:5060; branch=z9hG4bK-2f059
Identifies the location where the
response is to be sent.
Max-Forwards:70 Limits the number of hops the request
will make on the way to its destination.
From: Alice A.
<sip:[e-mail]>;tag=1121137
User originating this request. Includes a
unique tag.
To: Bob B. <sip:[e-mail]> User being invited, as specified
originally.
Call-ID: 2388990012@alice_ws.hp.com Globally unique ID of this call.
CSeq: 1 INVITE Command sequence. Identifies
transaction.
Contact:<sip:[e-mail]> Direct route to contact Alice in further
requests.
Subject: Lunch today. Call subject and/or nature.
Content-Length: 182 Number of bytes in the body.