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mail.jabber.org/pipermail/standards/2007-April/015053.html - 5k -

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Posted by crouse

INVITE—A caller sends this message to request that another endpoint join a SIP session, such as a conference or a call. This message can also be sent during a call to change session parameters.

Example :SIP INVITE Message

SIP-GW#debug ccsip messages
Sent:!Request-URI (Uniform Resource Identifier) field

!This is the SIP address, or SIP URL, that the INVITE is sent to

INVITE sip:3401@10.6.2.10:5060 SIP/2.0!Each device that handles the packet adds its IP address to the VIA
field
Via: SIP/2.0/UDP 10.6.3.1:5060;branch=z9hG4bKA1798!The calling party. A tag identifies this series of messages

From: ;tag=105741C-1D5E!The called party

To:
Date: Fri, 06 Jan 2006 05:35:01 GMT!Unique identifier for this call

Call-ID: E937365B-2C0C11D6-802FA93D-4772A3BB@10.6.3.1!Extensions supported include reliable provisional responses and timer
refreshers
Supported: 100rel, timer!Minimum value for session interval

Min-SE: 1800
Cisco-Guid: 3892269682-738988502-2150410557-1198695355!Identifies the device that originated the INVITE

User-Agent: Cisco-SIPGateway/IOS-12.x!List of methods that are supported

Allow: INVITE, OPTIONS, BYE, CANCEL, ACK, PRACK, COMET, REFER, SUBSCRIBE, NOTIFY,
INFO, UPDATE, REGISTER!Identifies call sequence number and method for this call

CSeq: 101 INVITE!Max number of proxies or gateways that can forward this message

Max-Forwards: 70
Remote-Party-ID: ;party=calling;screen=no;privacy=off
Timestamp: 1014960901!Identifies the user agent client, for return messages

Contact:
Expires: 180
Allow-Events: telephone-event!This INVITE carries an SDP message

Content-Type: application/sdp
Content-Length: 202

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Posted by sagitraz

Start Line: The UAS (not identified yet) is requesting (with an invite method) that a session be initiated with John Reynold on the Columbia.edu Proxy using SIP Version 2.0
From: Now we know who the UAC is. A displayable text identifies his name and position. The SIP address is a SIP phone number that can be redirected to his work SIP phone or his cell phone.
To: Repeats the Start Line URI but adds a displayable text.
Call-ID: Every request and response involved with the call will carry this ID.
C-Seq: All messages relating to this Invite will have carry this identifier.
Via: Provides SIP version, transport method, IP address, and port where Dan can be reached. Every SIP server this message flows through can add a VIA line referring to themselves.
Record-Route – As the packet traveled from Dan to John, it was routed through several servers that want to be kept “in the loop”. Each adds its address as the packet passes through.
Contact: Dan called from work. This URI specifies his work SIP phone.
Content-Type- The Message Body will contain an SDP that identifies options and codecs that Dan’s work phone can handle.
Content-length – The Message Body will be 195 bytes long.
All the rest – are SDP parameters. The Proxy will help Dan’s phone negotiate with John’s for which options they will end up using.

Example of INVITE message is below

Frame 31 (607 bytes on wire, 607 bytes captured)
Ethernet II, Src: Intraser_04:04:aa (00:60:5b:04:04:aa), Dst: Ditech_78:04:0a (00:d0:02:78:04:0a)
Internet Protocol, Src: 172.20.101.203 (172.20.101.203), Dst: 172.20.231.212 (172.20.231.212)
User Datagram Protocol, Src Port: 5060 (5060), Dst Port: 53615 (53615)
Source port: 5060 (5060)
Destination port: 53615 (53615)
Length: 573
Checksum: 0xb6e8 [correct]
Session Initiation Protocol
Request-Line: INVITE sip:2100030002@172.20.231.212:53615 SIP/2.0
Method: INVITE
Resent Packet: False
Message Header
Via: SIP/2.0/UDP 172.20.101.203;branch=z9hG4bK-45b4e72d-00000155
To:
SIP to address: sip:2100030002@172.20.231.212:53615
From: ;tag=13568
SIP from address: sip:9720040001@172.20.101.203
SIP tag: 13568
Call-ID: 1169483565-274@Spurs
CSeq: 1 INVITE
Content-Type: application/sdp
Contact: sip:9720040001@172.20.101.203
Contact Binding: sip:9720040001@172.20.101.203
URI: sip:9720040001@172.20.101.203r
SIP contact address: sip:9720040001@172.20.101.203r
Allow: INVITE
Expires: 330
Max-Forwards: 70
Supported: 100rel
Content-Length: 148
Message body
Session Description Protocol
Session Description Protocol Version (v): 0
Owner/Creator, Session Id (o): - 268750848 1165621310 IN IP4 172.20.235.138
Owner Username: -
Session ID: 268750848
Session Version: 1165621310
Owner Network Type: IN
Owner Address Type: IP4
Owner Address: 172.20.235.138
Session Name (s): -
Connection Information (c): IN IP4 172.20.235.138
Connection Network Type: IN
Connection Address Type: IP4
Connection Address: 172.20.235.138
Time Description, active time (t): 0 0
Session Start Time: 0
Session Stop Time: 0
Session Attribute (a): sendrecv
Media Description, name and address (m): audio 5370 RTP/AVP 0
Media Type: audio
Media Port: 5370
Media Proto: RTP/AVP
Media Format: ITU-T G.711 PCMU
Media Attribute (a): rtpmap:0 PCMU/8000
Media Attribute Fieldname: rtpmap
Media Attribute Value: 0 PCMU/8000

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Posted by snjysanjay05