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

Call-ID: [e-mail]
Content-Type: application/sdp
CSeq: 1 INVITE
Contact: <sip:telecom@16.188.155.140>
Content-Length: 187
v=0
o=user1 51633745 1348648134 IN IP4 16.188.155.140
s=Interactive Conference
c=IN IP4 224.2.4.4/127
t=0 0
m=audio 3456 RTP/AVP 0 22
a=rtpmap:22 application/g723.1
The following are the different parts of a request:
First Line
Contains the method name, such as INVITE.
Via
Indicates the transport used for transaction and
contains the address at which the caller is
expecting responses to the request.
From
Contains a display name, and a SIP or secure SIP
(SIPS) uniform resource identifier (URI) that
indicates the originator of the request.
To Contains the display name (TPU) and a SIP or a
SIPS URI towards which the request was originally
directed.
Subject
Contains the subject line for the call
Call ID
Contains a globally unique identifier for this call
generated by the combination of a random string
and the end point’s host name or IP address.
Content-Type
Contains a description of the message body.
Command sequence (CSeq)
Contains an integer and a method name.
Contact
Contains a SIP or SIPS URI that represents a direct
route to contact the end point. Contact usually
contains a username that is a fully qualified
domain name.
Content-Length
Contains an octet (byte) count of the message body.
A valid SIP request formulated by a user agent client must contain the following header
fields: To, From, CSeq, Call-ID, Max-Forwards, and Via. These header fields are
the fundamental building blocks of a SIP message, because they provide most of the
critical message routing services including addressing of messages, routing of responses,
limiting message propagation, ordering of messages, and the unique identification of
transactions.
Following are the SIP Request method names, as defined in RFC 3261 (Session Initiation
Protocol):
SIP Messages 23