HP-UX Java SIP Stack Programmer's Guide (February 2008)

Table 1-3 Message Parts
DescriptionSIP Message Name
Denotes the beginning of a SIP message. A start line can be either a
request or a response. A request start line contains a method name, the
SIP URI to which the message is sent, and the SIP version number. The
response start line contains the SIP version number, the status code, and
the description for the response phrase.
Following are sample SIP start lines:
• Request start line
INVITE sip:[e-mail] SIP/2.0
• Response start line
SIP/2.0 200 OK
Start Line
Contains fields that provide additional information about a message,
such as To, From, Subject, and Via.
Certain header fields, such as To, From, and Subject, contain only a
single header field value and appear only once in the header. Certain
header fields, such as Via, Contact, and Route, can appear multiple
times in a header and can contain multiple values separated by a comma.
Following is a sample SIP header:
From: <sip:[e-mail]>
To: TPU <sip:[e-mail]>
Subject: Confcall
Call-ID: [e-mail]
Content-Type: application/sdp
CSeq: 1 INVITE
Header
Contains information about the message that must be passed to the
receiver. The message can be either a plain text message or a multimedia
message. The session description protocol (SDP) describes the session
parameters for a multimedia message. The message body is independent
of the SIP protocol and can contain any information.
Message Body
Call Flow Scenarios
This section describes the interaction between SIP entities in various call flow scenarios.
This section addresses the following topics:
• “Basic Call Setup and Teardown”
• “Using the Proxy Server” (page 30)
• “Using the Redirect Server” (page 32)
Basic Call Setup and Teardown
This section discusses the various SIP requests and responses exchanged between user
agents during a basic call setup and teardown.
Call Flow Scenarios 29