Internet Engineering Task Force M. HASEBE
Internet-Draft NTT-East
Expiration:August 14th, 2005 J. KOSHIKO
NTT-East
Y. SUZUKI
NTT-East
T. YOSHIKAWA
NTT-East
Feb 14, 2005
Session Initiation Protocol Semi Regular Examples
draft-hasebe-sipping-semi-regular-examples-00
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Copyright Notice
Copyright (C) The Internet Society (2005). All Rights Reserved.
Abstract
This document gives examples of Session Initiation Protocol (SIP)
semi-regular call flows. The elements in these call flows include
SIP User Agents andü@Clients. The scenarios include SIP session
establishment. Call flow diagrams and message details are shown.
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Table of Contents
1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. General Assumptions. . . . . . . . . . . . . . . . . . . 3
1.2. Legend for Message Flows . . . . . . . . . . . . . . . . 3
1.3. SIP Protocol Assumptions . . . . . . . . . . . . . . . . 4
2. Semi Regular . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. CANCEL crossover . . . . . . . . . . . . . . . . . . . . 5
2.2. BYE crossover. . . . . . . . . . . . . . . . . . . . . . 8
2.3. Session timer crossover(re-INVITE,BYE) . . . . . . . . . 12
2.4. REFER crossover(REFER,BYE) . . . . . . . . . . . . . . . 16
2.5. A BYE is sent immediately after sending of a re-INVITE . 20
3. References . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4. Intellectual Property Statement. . . . . . . . . . . . . . . . 25
5. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 25
1. Overview
The call flows shown in this document were developed in the design of
a SIP IP communications network.
These are some difficult interpretative examples about behavior of user
agent followed by RFCs.
In various situations which may happen when SIP is implemented,
especially,when a situation which serves as a norm of inplementing in
RFC is not illustrated, by showing operation of a terminal or a server
as an example, it will be a help to a SIP implementers.
For a example, the sequence which CANCEL and 200OK for INVITE cross each
other can be considered. INVITE transaction is obviously present on the
UAC, when the UAC sends a CANCEL message. And when the UAS sends a 200 OK
response for INVITE and then receives CANCEL message, there is not INVITE
transaction on the UAS. In such a case, In such a case, what response
does UAS reply for the CANCEL.
This document clarifies SIP UA behavior when messages cross each other
as semi-regular condition.
By clarifying operation under semi-regular condition, it is avoided the
difference of the interpretation between implementations.
And it is expected that interoperability is more progressed.
It is the hope of the authors that this document will be useful for
SIP implementers, designers, and protocol researchers alike and will
help further the goal of a standard implementation of RFC 3261 [1].
These call flows are based on the current version 2.0 of SIP in RFC
3261 [1] with SDP usage described in RFC 3264 [2].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in BCP 14, RFC 2119 [4].
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1.1. General Assumptions
A number of architecture, network, and protocol assumptions underlie
the call flows in this document. Note that these assumptions are not
requirements. They are outlined in this section so that they may be
taken into consideration and to aid in the understanding of the call
flow examples.
These flows show TCP, TLS, and UDP for transport. See the discussion
in RFC 3261 for details on the transport issues for SIP.
1.2. Legend for Message Flows
Dashed lines (---) and slash lines (/,\) represent signaling messages
that are mandatory to the call scenario.(X) represent crossover of
signaling messages. The arrow indicates the direction of message flow.
Double dashed lines (===) represent media paths between network
elements.
Messages with parentheses around their name represent optional
messages.
Messages are identified in the Figures as F1, F2, etc. This
references the message details in the list that follows the Figure.
Comments in the message details are shown in the following form:
/* Comments. */
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1.3. SIP Protocol Assumptions
This document does not prescribe the flows precisely as they are
shown, but rather the flows illustrate the principles for best
practice. They are best practices usages (orderings, syntax,
selection of features for the purpose, handling of error) of SIP
methods, headers and parameters. IMPORTANT: The exact flows here
must not be copied as is by an implementer due to specific incorrect
characteristics that were introduced into the document for
convenience and are listed below. To sum up, the basic flows
represent well-reviewed examples of SIP usage, which are best common
practice according to IETF consensus.
For simplicity in reading and editing the document, there are a
number of differences between some of the examples and actual SIP
messages. For example, Call-IDs are often repeated, and CSeq counts often begin
at 1. Header fields are usually shown in the same order. Usually
only the minimum required header field set is shown, others that
would normally be present such as Accept, Allow, etc are
not shown.
Actors:
Element Display Name URI IP Address
------- ------------ --- ----------
User Agent Alice alice@atlanta.example.com 192.0.2.101
User Agent Bob bob@biloxi.example.com 192.0.2.201
2. Semi Regular
This section details semi-regular between two SIP User
Agents (UAs): Alice and Bob. Alice (sip:alice@atlanta.example.com)
and Bob (sip:bob@biloxi.example.com) are assumed to be SIP phones or
SIP-enabled devices.
When messages cross each other as semi-regular condition, it clarifies
how SIP UA should behave.
For a example, the sequence which CANCEL and 200OK for INVITE cross each
other can be considered. INVITE transaction is obviously present on the
UAC, when the UAC sends a CANCEL message. And when the UAS sends a 200 OK
response for INVITE and then receives CANCEL message, there is not INVITE
transaction on the UAS anymore. Actually, the UAS state-changes itself
into confirmed dialog already.
The one of examples for operating in the above semi-regular case is shown
to below.
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2.1. CANCEL crossover
Alice Bob
| |
| INVITE F1 |
|----------------------->|
| 180 Ringing F2 |
|<-----------------------|
| |
|CANCEL F3 200 OK F4 |
|--------- ----------|
| \ / |
| X |
| / \ |
|<-------- --------->|
| |
| ACK F6 481 F5 |
|--------- ----------|
| \ / |
| X |
| / \ |
|<-------- --------->|
| |
| Both Way RTP Media |
|<======================>|
| |
In this scenario, Alice sends a CANCEL and Bob sends a 200 OK response
to the initial INVITE message at the same time. And then Bob sends a
481 response replying to CANCEL from Alice.
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Message Details
F1 INVITE Alice -> Bob
INVITE sip:bob@biloxi.example.com SIP/2.0
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
Max-Forwards: 70
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Contact: <sip:alice@client.atlanta.example.com;transport=tcp>
Content-Type: application/sdp
Content-Length: 151
v=0
o=alice 2890844526 2890844526 IN IP4 client.atlanta.example.com
s=-
c=IN IP4 192.0.2.101
t=0 0
m=audio 49172 RTP/AVP 0
a=rtpmap:0 PCMU/8000
F2 180 Ringing Bob -> Alice
SIP/2.0 180 Ringing
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
;received=192.0.2.101
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
Content-Length: 0
F3 CANCEL Alice -> Bob
CANCEL sip:bob@client.biloxi.example.com;transport=tcp SIP/2.0
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bd5
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 CANCEL
Contact: <sip:alice@client.atlanta.example.com;transport=tcp>
Content-Length: 0
/* When Alice sends CANCEL, INVITE transaction exists. */
F4 200 OK Bob -> Alice
SIP/2.0 481 Call/Transaction Dose Not Exist
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bd5
;received=192.0.2.101
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
Content-Length: 0
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/* Alice sends a CANCEL and Bob sends a 200 OK response to the
initial INVITE message at the same time. In the bob side,
an INVITE transaction is completed by sending of the final
response (200 OK). A 200 OK and a CANCEL crossed each other and
inconsistency has arisen in the state of INVITE transaction
of Alice and Bob. */
F5 481 Call/Transaction Dose Not Exist Bob -> Alice
SIP/2.0 481 Call/Transaction Dose Not Exist
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bd5
;received=192.0.2.101
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 CANCEL
Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
Content-Length: 0
/* The INVITE transaction which is targeted from the CANCEL request
already sent the final response, so Bob returns a 481 response. */
F6 ACK Alice -> Bob
ACK sip:bob@client.biloxi.example.com SIP/2.0
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bd5
Max-Forwards: 70
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 ACK
Content-Length: 0
/* Bob has sent the final response, and a CANCEL becomes invalid.
RTP streams are established.*/
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2.2. BYE crossover
Alice Bob
| |
| INVITE F1 |
|----------------------->|
| 180 Ringing F2 |
|<-----------------------|
| |
| 200 OK F3 |
|<-----------------------|
| ACK F4 |
|----------------------->|
| Both Way RTP Media |
|<======================>|
| |
| BYE F5 BYE F6 |
|--------- ----------|
| \ / |
| X |
| / \ |
|<-------- --------->|
| |
| 481 F8 481 F7 |
|--------- ----------|
| \ / |
| X |
| / \ |
|<-------- --------->|
| |
| |
In this scenario, Alice and Bob sends a BYE at the same time.
A session is ended shortly after a BYE request is passed to a
client transaction.According to 15.1.1 of RFC3261, an opportunity
to complete a dialog seems to be a response or timeout of a BYE.
Therefore, UA can transmit and receive a request normally until it
receives a response. However, when UA sends a BYE, it is determined
that the dialog is completed. So, in this scenario, it recommends
that UA ends a dialog immediately after sending a BYE.
(In section 2.4, the example from which the result obtained
depending on the timing of a dialog end differs is shown. )
Operation of above UA, both a BYE of Alice and Bob is returned by
a 481.
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Message Details
F1 INVITE Alice -> Bob
INVITE sip:bob@biloxi.example.com SIP/2.0
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
Max-Forwards: 70
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Contact: <sip:alice@client.atlanta.example.com;transport=tcp>
Content-Type: application/sdp
Content-Length: 151
v=0
o=alice 2890844526 2890844526 IN IP4 client.atlanta.example.com
s=-
c=IN IP4 192.0.2.101
t=0 0
m=audio 49172 RTP/AVP 0
a=rtpmap:0 PCMU/8000
F2 180 Ringing Bob -> Alice
SIP/2.0 180 Ringing
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
;received=192.0.2.101
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
Content-Length: 0
F3 200 OK Bob -> Alice
SIP/2.0 200 OK
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
;received=192.0.2.101
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
Content-Type: application/sdp
Content-Length: 147
v=0
o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com
s=-
c=IN IP4 192.0.2.201
t=0 0
m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000
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F4 ACK Alice -> Bob
ACK sip:bob@client.biloxi.example.com SIP/2.0
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bd5
Max-Forwards: 70
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 ACK
Content-Length: 0
/* RTP streams are established between Alice and Bob */
/* Bob Hangs Up with Alice. Note that the CSeq is NOT 2, since
Alice and Bob maintain their own independent CSeq counts.
(The INVITE was request 1 generated by Alice, and the BYE is
request 1 generated by Bob) */
F5 BYE Alice -> Bob
BYE sip:bob@client.biloxi.example.com SIP/2.0
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bKnashds8
Max-Forwards: 70
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 2 BYE
Content-Length: 0
/* Alice terminates a session by having sent a BYE.
RTP streams are terminated. */
/* A session is terminated by sending a BYE. Although a dialog is
completed by receiving a response or a timeout, when UA sends a
BYE, it is determined that the dialog is completed, a dialog is
also terminated ignited by BYE sending. */
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F6 BYE Bob -> Alice
BYE sip:alice@client.atlanta.example.com SIP/2.0
Via: SIP/2.0/TCP client.biloxi.example.com:5060;branch=z9hG4bKnashds7
Max-Forwards: 70
From: Bob <sip:bob@biloxi.example.com>;tag=8321234356
To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 BYE
Content-Length: 0
/* Bob has also transmitted BYE simultaneously with Alice.
Bob terminates a session and dialog. */
F7 481 Call/Transaction Does Not Exist Bob -> Alice
SIP/2.0 481 Call/Transaction Does Not Exist
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bKnashds8
;received=192.0.2.201
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 2 BYE
Content-Length: 0
/* Since the dialog is already terminated, the BYE is returned
by a 481. */
F8 481 Call/Transaction Does Not Exist Alice -> Bob
SIP/2.0 481 Call/Transaction Does Not Exist
Via: SIP/2.0/TCP client.biloxi.example.com:5060;branch=z9hG4bKnashds7
;received=192.0.2.201
From: Bob <sip:bob@biloxi.example.com>;tag=8321234356
To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 BYE
Content-Length: 0
/* Since Bob has terminated the dialog by sending a BYE,
a BYE which Alice sent is also returned by a 481. */
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2.3. Session timer crossover(re-INVITE,BYE)
Alice Bob
| |
| INVITE F1 |
|----------------------->|
| 180 Ringing F2 |
|<-----------------------|
| |
| 200 OK F3 |
|<-----------------------|
| ACK F4 |
|----------------------->|
| Both Way RTP Media |
|<======================>|
| |
| BYE F5 re-INVITE F6|
|--------- ----------|
| \ / |
| X |
| / \ |
|<-------- --------->|
| |
| 481 F8 200 F7 |
|--------- ----------|
| \ / |
| X |
| / \ |
|<-------- --------->|
| ACK F9 |
|<-----------------------|
| |
In this scenario, Bob sends a re-INVITE, and Alice sends a BYE
at the same time. The re-INVITE of Bob is returned by a 481.
Although TU of Bob has terminated the dialog by BYE, since the
client transaction of a re-INVITE still exists, a client
transaction sends ACK to 481 responses.
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Message Details
F1 INVITE Alice -> Bob
INVITE sip:bob@biloxi.example.com SIP/2.0
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
Supported: timer
Session-Expires: 300
Max-Forwards: 70
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Contact: <sip:alice@client.atlanta.example.com;transport=tcp>
Content-Type: application/sdp
Content-Length: 151
v=0
o=alice 2890844526 2890844526 IN IP4 client.atlanta.example.com
s=-
c=IN IP4 192.0.2.101
t=0 0
m=audio 49172 RTP/AVP 0
a=rtpmap:0 PCMU/8000
F2 180 Ringing Bob -> Alice
SIP/2.0 180 Ringing
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
;received=192.0.2.101
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
Content-Length: 0
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F3 200 OK Bob -> Alice
SIP/2.0 200 OK
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
;received=192.0.2.101
Require: timer
Session-Expires: 300;refresher=uas
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
Content-Type: application/sdp
Content-Length: 147
v=0
o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com
s=-
c=IN IP4 192.0.2.201
t=0 0
m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000
/* Since there was no specification of refresher, Bob sets up
refresher=uas. */
F4 ACK Alice -> Bob
ACK sip:bob@client.biloxi.example.com SIP/2.0
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bd5
Supported: timer
Session-Expires: 300
Max-Forwards: 70
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 ACK
Content-Length: 0
/* RTP streams are established between Alice and Bob */
/* Bob Hangs Up with Alice. Note that the CSeq is NOT 2, since
Alice and Bob maintain their own independent CSeq counts.
(The INVITE was request 1 generated by Alice, and the BYE is
request 1 generated by Bob) */
F5 BYE Alice -> Bob
BYE sip:bob@client.biloxi.example.com SIP/2.0
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bKnashds8
Max-Forwards: 70
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 2 BYE
Content-Length: 0
/* Alice sends a BYE and terminates a session and dialog. */
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F6 re-INVITE Bob -> Alice
INVITE sip:alice@client.atlanta.example.com SIP/2.0
Via: SIP/2.0/TCP client.biloxi.example.com:5060;branch=z9hG4bKnashds7
Session-Expires: 300;refresher=uac
Max-Forwards: 70
From: Bob <sip:bob@biloxi.example.com>;tag=8321234356
To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Content-Length: 0
/* Alice sends a BYE, and Bob sends a re-INVITE at same time.
In the Alice side, the dialog is completed, and in the Bob side,
the dialog is terminated, the state of a dialog is mismatching. */
F7 200 OK Bob -> Alice
SIP/2.0 200 OK
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bKnashds8
;received=192.0.2.201
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 2 BYE
Content-Length: 0
F8 481 Call/Transaction Does Not Exist Alice -> Bob
SIP/2.0 481 Call/Transaction Does Not Exist
Via: SIP/2.0/TCP client.biloxi.example.com:5060;branch=z9hG4bKnashds7
;received=192.0.2.201
From: Bob <sip:bob@biloxi.example.com>;tag=8321234356
To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Content-Length: 0
/* Since Alice has already terminated the dialog by a BYE,
it returns a 481. */
F9 ACK Bob -> Alice
ACK sip:bob@client.biloxi.example.com SIP/2.0
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bKnashds8
;received=192.0.2.201
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Content-Length: 0
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2.4. REFER crossover(REFER,BYE)
Alice Bob
| |
| INVITE F1 |
|----------------------->|
| 180 Ringing F2 |
|<-----------------------|
| |
| 200 OK F3 |
|<-----------------------|
| ACK F4 |
|----------------------->|
| Both Way RTP Media |
|<======================>|
| |
| BYE F5 REFER F6 |
|--------- ----------|
| \ / |
| X |
| / \ |
|<-------- --------->|
| |
| 481 F8 200 F7 |
|--------- ----------|
| \ / |
| X |
| / \ |
|<-------- --------->|
| |
| |
In this scenario, Bob sends REFER, and Alice sends BYE at
the same time. REFER is sent as a method in the same dialog.
In the Alice side, as 2.2 described, a dialog is terminated
ignited by sending a BYE request, and Alice returns a 481 to
REFER.
(If a dialog is terminated after receiving the response of a
BYE (with or timeout), Alice returns 202 to the REFER and the
REFER method is successful. Also when a dialog is terminated,
it is not clear whether UA continues call transfer. )
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Message Details
F1 INVITE Alice -> Bob
INVITE sip:bob@biloxi.example.com SIP/2.0
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
Supported: timer
Session-Expires: 300
Max-Forwards: 70
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Contact: <sip:alice@client.atlanta.example.com;transport=tcp>
Content-Type: application/sdp
Content-Length: 151
v=0
o=alice 2890844526 2890844526 IN IP4 client.atlanta.example.com
s=-
c=IN IP4 192.0.2.101
t=0 0
m=audio 49172 RTP/AVP 0
a=rtpmap:0 PCMU/8000
F2 180 Ringing Bob -> Alice
SIP/2.0 180 Ringing
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
;received=192.0.2.101
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
Content-Length: 0
F3 200 OK Bob -> Alice
SIP/2.0 200 OK
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
;received=192.0.2.101
Require: timer
Session-Expires: 300;refresher=uas
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
Content-Type: application/sdp
Content-Length: 147
v=0
o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com
s=-
c=IN IP4 192.0.2.201
t=0 0
m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000
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F4 ACK Alice -> Bob
ACK sip:bob@client.biloxi.example.com SIP/2.0
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bd5
Supported: timer
Session-Expires: 300
Max-Forwards: 70
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 ACK
Content-Length: 0
/* RTP streams are established between Alice and Bob */
/* Bob Hangs Up with Alice. Note that the CSeq is NOT 2, since
Alice and Bob maintain their own independent CSeq counts.
(The INVITE was request 1 generated by Alice, and the BYE is
request 1 generated by Bob) */
F5 BYE Alice -> Bob
BYE sip:bob@client.biloxi.example.com SIP/2.0
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bKnashds8
Max-Forwards: 70
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 2 BYE
Content-Length: 0
/* Alice sends a BYE and terminates a session and dialog. */
F6 REFER Bob -> Alice
REFER sip:alice@client.atlanta.example.com SIP/2.0
Via: SIP/2.0/TCP client.biloxi.example.com:5060;branch=z9hG4bKnashds7
Session-Expires: 300;refresher=uac
Max-Forwards: 70
From: Bob <sip:bob@biloxi.example.com>;tag=8321234356
To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 REFER
Content-Length: 0
/* Alice sends a BYE, and Bob sends a REFER at same time.
The REFER is sent as a method in the same dialog.
In the Alice side, the dialog is completed, and in the Bob side,
the dialog is terminated,the state of a dialog is mismatching. */
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F7 200 OK Bob -> Alice
SIP/2.0 200 OK
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bKnashds8
;received=192.0.2.201
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 2 BYE
Content-Length: 0
F8 481 Call/Transaction Does Not Exist Alice -> Bob
SIP/2.0 481 Call/Transaction Does Not Exist
Via: SIP/2.0/TCP client.biloxi.example.com:5060;branch=z9hG4bKnashds7
;received=192.0.2.201
From: Bob <sip:bob@biloxi.example.com>;tag=8321234356
To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 REFER
Content-Length: 0
/* Since Alice has already terminated the dialog by a BYE,
it returns a 481. */
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2.5. A BYE is sent immediately after sending of a re-INVITE
Alice Bob
| |
| INVITE F1 |
|----------------------->|
| 180 Ringing F2 |
|<-----------------------|
| |
| 200 OK F3 |
|<-----------------------|
| ACK F4 |
|----------------------->|
| Both Way RTP Media |
|<======================>|
| |
| re-INVITE F5 |
|<-----------------------|
| 200 F7 BYE F6 |
|--------- ----------|
| \ / |
| X |
| / \ |
|<-------- --------->|
| 200 OK F8 |
|----------------------->|
| |
| |
In this scenario, Bob sends a BYE immediately after sending
of a re-INVITE,
(A user is not conscious of refresher sent automatically.
For example, in the case of a telephone application, placing
a receiver immediately after refresher is considered enough. )
When Alice receives BYE, even if it terminates a dialog and
does not receive ACK, it stops resending of 200 OK. Since ACK
of 2xx responses is not a server transaction, it is that a UAS
core transmits directly. It differs from the case of an error
response of 2.4. With a UAS core, since the dialog which matches
200 OK received is terminated, 200 OK is disregarded, without
sending ACK.
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Message Details
F1 INVITE Alice -> Bob
INVITE sip:bob@biloxi.example.com SIP/2.0
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
Supported: timer
Session-Expires: 300
Max-Forwards: 70
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Contact: <sip:alice@client.atlanta.example.com;transport=tcp>
Content-Type: application/sdp
Content-Length: 151
v=0
o=alice 2890844526 2890844526 IN IP4 client.atlanta.example.com
s=-
c=IN IP4 192.0.2.101
t=0 0
m=audio 49172 RTP/AVP 0
a=rtpmap:0 PCMU/8000
F2 180 Ringing Bob -> Alice
SIP/2.0 180 Ringing
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
;received=192.0.2.101
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
Content-Length: 0
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F3 200 OK Bob -> Alice
SIP/2.0 200 OK
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
;received=192.0.2.101
Require: timer
Session-Expires: 300;refresher=uas
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
Content-Type: application/sdp
Content-Length: 147
v=0
o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com
s=-
c=IN IP4 192.0.2.201
t=0 0
m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000
F4 ACK Alice -> Bob
ACK sip:bob@client.biloxi.example.com SIP/2.0
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bd5
Supported: timer
Session-Expires: 300
Max-Forwards: 70
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
To: Bob <sip:bob@biloxi.example.com>;tag=8321234356
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 ACK
Content-Length: 0
/* RTP streams are established between Alice and Bob */
/* Bob Hangs Up with Alice. Note that the CSeq is NOT 2, since
Alice and Bob maintain their own independent CSeq counts.
(The INVITE was request 1 generated by Alice, and the BYE is
request 1 generated by Bob) */
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F5 re-INVITE Bob -> Alice
INVITE sip:alice@client.atlanta.example.com SIP/2.0
Via: SIP/2.0/TCP client.biloxi.example.com:5060;branch=z9hG4bKnashds7
Session-Expires: 300;refresher=uac
Max-Forwards: 70
From: Bob <sip:bob@biloxi.example.com>;tag=8321234356
To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Content-Length: 0
F6 BYE Bob -> Alice
BYE sip:alice@client.atlanta.example.com SIP/2.0
Via: SIP/2.0/TCP client.biloxi.example.com:5060;branch=z9hG4bKnashds8
Max-Forwards: 70
From: Bob <sip:bob@biloxi.example.com>;tag=8321234356
To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 2 BYE
Content-Length: 0
/* Bob sends a BYE immediately after sending of a re-INVITE,
Bob terminates a session and dialog, without receiving the
response of re-INVITE. */
F7 200 OK Alice -> Bob
SIP/2.0 200 OK
Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bKnashds7
;received=192.0.2.201
From: Bob <sip:bob@biloxi.example.com>;tag=8321234356
To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 1 INVITE
Content-Length: 0
/* Bob sends a BYE, and Alice returns 200 OK to a re-INVITE.
The state of a dialog is mismatching.*/
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F8 200 OK Alice -> Bob
SIP/2.0 200 OK
Via: SIP/2.0/TCP client.biloxi.example.com:5060;branch=z9hG4bKnashds8
;received=192.0.2.201
From: Bob <sip:bob@biloxi.example.com>;tag=8321234356
To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
Call-ID: 3848276298220188511@atlanta.example.com
CSeq: 2 BYE
Content-Length: 0
/* The UAC core of Bob does not send a ACK after receiving 200 OK to
a re-INVITE.(Bob has terminated the dialog by sending of a BYE.)
The UAS core of Alice does not resend 200 OK to a re-INVITE.
(Since the dialog is terminated by reception of BYE, 200 OK dose
not resend, even if it does not receive ACK from Bob.) */
3. References
[1] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002.
[2] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with
SDP", RFC 3264, April 2002.
[3] Johnston, A., Donovan, S., Sparks, R., Cunningham, C. and K.
Summers, "Session Initiation Protocol (SIP) Basic Call Flow
Examples", BCP 75, RFC 3665, December 2003.
[4] Johnston, A., Donovan, S., Sparks, R., Cunningham, C. and K.
Summers, "Session Initiation Protocol (SIP) Public Switched
Telephone Network (PSTN) Call Flows", BCP 76, RFC 3666, December
2003.
[5] Sparks, R., "The Session Initiation Protocol (SIP) Refer
Method", RFC 3515, April 2003.
Hasebe [Page 24]
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4. Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
5. Authors' Addresses
All listed authors actively contributed large amounts of text to this
document.
Miki Hasebe
NTT-east Corporation
19-2 Nishi-shinjuku 3-chome Shinjuku-ku Tokyo 163-8019 Japan
EMail: hasebe.miki@rdc.east.ntt.co.jp
Jun Koshiko
NTT-east Corporation
19-2 Nishi-shinjuku 3-chome Shinjuku-ku Tokyo 163-8019 Japan
EMail: j.koshiko@rdc.east.ntt.co.jp
Yasushi Suzuki
NTT-east Corporation
19-2 Nishi-shinjuku 3-chome Shinjuku-ku Tokyo 163-8019 Japan
EMail: suzuki.yasushi@rdc.east.ntt.co.jp
Tomoyuki Yoshikawa
NTT-east Corporation
19-2 Nishi-shinjuku 3-chome Shinjuku-ku Tokyo 163-8019 Japan
EMail: tomoyuki.yoshikawa@rdc.east.ntt.co.jp
Hasebe [Page 25]
Internet Draft Semi Regular Examples Feb 14th,2005
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Disclaimer of Validity
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2004). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
The Expiration date for this Internet Draft is:
August 14th, 2005
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