Internet Engineering Task Force M. HASEBE Internet-Draft NTT-East Expiration: Jan 7th, 2006 J. KOSHIKO NTT-East Y. SUZUKI NTT-East T. YOSHIKAWA NTT-East Jul 8, 2005 Session Initiation Protocol Exceptional Procedure Examples draft-hasebe-sipping-exceptional-procedure-example-00 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Copyright Notice Copyright (C) The Internet Society (2005). All Rights Reserved. Abstract This document gives examples of Session Initiation Protocol (SIP) exceptional-procedure call flows. This is the problem (or confusing) scenario and this is the best practice to handle it. The elements in these call flows include SIP User Agents and Clients. The scenarios include SIP session establishment. Call flow diagrams and message details are shown. Hasebe [Page 1] Internet Draft Exceptional Procedure Examples Jul 8th,2005 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. Exceptional Procedure. . . . . . . . . . . . . . . . . . . . . 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 2.6. re-INVITE crossover. . . . . . . . . . . . . . . . . . . 23 2.7. Initial INVITE retransmission. . . . . . . . . . . . . . 30 2.8. Early Dialog . . . . . . . . . . . . . . . . . . . . . . 32 2.9. CANCEL crossover via a stateful proxy. . . . . . . . . . 41 3. References . . . . . . . . . . . . . . . . . . . . . . . . . . 47 4. Intellectual Property Statement. . . . . . . . . . . . . . . . 47 5. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 48 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, what responsedoes UAS reply for the CANCEL. This document clarifies SIP UA behavior when messages cross each other as exceptional-procedure condition. By clarifying operation under exceptional-procedure 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 Hasebe [Page 2] Internet Draft Exceptional Procedure Examples Jul 8th,2005 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]. 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. */ 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 Hasebe [Page 3] Internet Draft Exceptional Procedure Examples Jul 8th,2005 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 sip:alice@atlanta.example.com 192.0.2.101 User Agent Bob sip:bob@biloxi.example.com 192.0.2.201 User Agent Carol sip:carol@chicago.example.com 192.0.2.301 Proxy Server ss.atlanta.example.com 192.0.2.111 2. Exceptional Procedure This section details exceptional-procedure 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 exceptional-procedure 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 exceptional-procedure case is shown to below. 2.1. CANCEL crossover Alice Bob | | | INVITE F1 | |----------------------->| | 180 Ringing F2 | Hasebe [Page 4] Internet Draft Exceptional Procedure Examples Jul 8th,2005 |<-----------------------| | | |CANCEL F3 200 OK F4 | |--------- ----------| | \ / | | X | | / \ | |<-------- --------->| | | | ACK F6 481 F5 | |--------- ----------| | \ / | | X | | / \ | |<-------- --------->| | | | Both Way RTP Media | |<======================>| | BYE F7 | |----------------------->| | 200 F8 | |<-----------------------| | | | | 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 the CANCEL from Alice. At UAC, immediately after 200 OK receiving to an INVITE, it can terminate by BYE. It means that UAC transmits a BYE after 200 OK, "it just means that the software in his phone needs to maintain state for a short while in order to clean up properly." (RFC3261,15) In this sequence, it recommends terminating from the caller side by a BYE. Message Details F1 INVITE Alice -> Bob INVITE sip:bob@biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: Content-Type: application/sdp Hasebe [Page 5] Internet Draft Exceptional Procedure Examples Jul 8th,2005 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/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: Content-Length: 0 F3 CANCEL Alice -> Bob CANCEL sip:bob@biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 CANCEL Content-Length: 0 /* When Alice sends CANCEL, INVITE transaction exists. */ F4 200 OK Bob -> Alice SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: Content-Type: application/sdp Content-Length: 147 Hasebe [Page 6] Internet Draft Exceptional Procedure Examples Jul 8th,2005 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 /* 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/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 CANCEL Contact: 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/UDP client.atlanta.example.com:5060;branch=z9hG4bKnashds8 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob ;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.*/ F7 BYE Alice -> Bob Hasebe [Page 7] Internet Draft Exceptional Procedure Examples Jul 8th,2005 BYE sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bKnashds9 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 2 BYE Content-Length: 0 F8 200 OK Bob -> Alice SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bKnashds9 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 2 BYE Content-Length: 0 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 | | / \ | Hasebe [Page 8] Internet Draft Exceptional Procedure Examples Jul 8th,2005 |<-------- --------->| | | | | 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. Message Details F1 INVITE Alice -> Bob INVITE sip:bob@biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: 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/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Hasebe [Page 9] Internet Draft Exceptional Procedure Examples Jul 8th,2005 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: Content-Length: 0 F3 200 OK Bob -> Alice SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: 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/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob ;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 Hasebe [Page 10] Internet Draft Exceptional Procedure Examples Jul 8th,2005 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bKnashds8 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob ;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. */ F6 BYE Bob -> Alice BYE sip:alice@client.atlanta.example.com SIP/2.0 Via: SIP/2.0/UDP client.biloxi.example.com:5060;branch=z9hG4bKnashds7 Max-Forwards: 70 From: Bob ;tag=8321234356 To: Alice ;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/UDP client.atlanta.example.com:5060;branch=z9hG4bKnashds8 ;received=192.0.2.201 From: Alice ;tag=9fxced76sl To: Bob ;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 Hasebe [Page 11] Internet Draft Exceptional Procedure Examples Jul 8th,2005 Via: SIP/2.0/UDP client.biloxi.example.com:5060;branch=z9hG4bKnashds7 ;received=192.0.2.201 From: Bob ;tag=8321234356 To: Alice ;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. */ 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 Hasebe [Page 12] Internet Draft Exceptional Procedure Examples Jul 8th,2005 transaction sends ACK to 481 responses. Message Details F1 INVITE Alice -> Bob INVITE sip:bob@biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 Supported: timer Session-Expires: 300 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: 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/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: Content-Length: 0 F3 200 OK Bob -> Alice SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Require: timer Session-Expires: 300;refresher=uas From: Alice ;tag=9fxced76sl Hasebe [Page 13] Internet Draft Exceptional Procedure Examples Jul 8th,2005 To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: 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/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob ;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/UDP client.atlanta.example.com:5060;branch=z9hG4bKnashds8 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 2 BYE Content-Length: 0 Hasebe [Page 14] Internet Draft Exceptional Procedure Examples Jul 8th,2005 /* Alice sends a BYE and terminates a session and dialog. */ F6 re-INVITE Bob -> Alice INVITE sip:alice@client.atlanta.example.com SIP/2.0 Via: SIP/2.0/UDP client.biloxi.example.com:5060;branch=z9hG4bKnashds7 Session-Expires: 300;refresher=uac Max-Forwards: 70 From: Bob ;tag=8321234356 To: Alice ;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/UDP client.atlanta.example.com:5060;branch=z9hG4bKnashds8 ;received=192.0.2.201 From: Alice ;tag=9fxced76sl To: Bob ;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/UDP client.biloxi.example.com:5060;branch=z9hG4bKnashds7 ;received=192.0.2.201 From: Bob ;tag=8321234356 To: Alice ;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 Hasebe [Page 15] Internet Draft Exceptional Procedure Examples Jul 8th,2005 Via: SIP/2.0/UDP client.biloxi.example.com:5060;branch=z9hG4bKnashds7 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Content-Length: 0 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. ) Hasebe [Page 16] Internet Draft Exceptional Procedure Examples Jul 8th,2005 Message Details F1 INVITE Alice -> Bob INVITE sip:bob@biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 Supported: timer Session-Expires: 300 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: 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/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: Content-Length: 0 F3 200 OK Bob -> Alice SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Require: timer Session-Expires: 300;refresher=uas From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Hasebe [Page 17] Internet Draft Exceptional Procedure Examples Jul 8th,2005 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: 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/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob ;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/UDP client.atlanta.example.com:5060;branch=z9hG4bKnashds8 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob ;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 Hasebe [Page 18] Internet Draft Exceptional Procedure Examples Jul 8th,2005 REFER sip:alice@client.atlanta.example.com SIP/2.0 Via: SIP/2.0/UDP client.biloxi.example.com:5060;branch=z9hG4bKnashds7 Max-Forwards: 70 From: Bob ;tag=8321234356 To: Alice ;tag=9fxced76sl Call-ID: 3848276298220188511@atlanta.example.com Refer-To: sip:carol@cleveland.example.org Contact: 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. */ F7 200 OK Bob -> Alice SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bKnashds8 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;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/UDP client.biloxi.example.com:5060;branch=z9hG4bKnashds7 ;received=192.0.2.201 From: Bob ;tag=8321234356 To: Alice ;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. */ 2.5. A BYE is sent immediately after sending of a re-INVITE Alice Bob | | | INVITE F1 | |----------------------->| Hasebe [Page 19] Internet Draft Exceptional Procedure Examples Jul 8th,2005 | 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. Message Details F1 INVITE Alice -> Bob INVITE sip:bob@biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 Supported: timer Session-Expires: 300 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 3848276298220188511@atlanta.example.com Hasebe [Page 20] Internet Draft Exceptional Procedure Examples Jul 8th,2005 CSeq: 1 INVITE Contact: 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/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: Content-Length: 0 F3 200 OK Bob -> Alice SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Require: timer Session-Expires: 300;refresher=uas From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: 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 Hasebe [Page 21] Internet Draft Exceptional Procedure Examples Jul 8th,2005 F4 ACK Alice -> Bob ACK sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob ;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 re-INVITE Bob -> Alice INVITE sip:alice@client.atlanta.example.com SIP/2.0 Via: SIP/2.0/UDP client.biloxi.example.com:5060;branch=z9hG4bKnashds7 Session-Expires: 300;refresher=uac Max-Forwards: 70 From: Bob ;tag=8321234356 To: Alice ;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/UDP client.biloxi.example.com:5060;branch=z9hG4bKnashds8 Max-Forwards: 70 From: Bob ;tag=8321234356 To: Alice ;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 Hasebe [Page 22] Internet Draft Exceptional Procedure Examples Jul 8th,2005 SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bKnashds7 ;received=192.0.2.201 From: Bob ;tag=8321234356 To: Alice ;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.*/ F8 200 OK Alice -> Bob SIP/2.0 200 OK Via: SIP/2.0/UDP client.biloxi.example.com:5060;branch=z9hG4bKnashds8 ;received=192.0.2.201 From: Bob ;tag=8321234356 To: Alice ;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.) */ 2.6. re-INVITE crossover Alice Bob | | | INVITE F1 | |--------------------------->| | 180 Ringing F2 | |<---------------------------| | | | 200 OK F3 | |<---------------------------| | ACK F4 | |--------------------------->| | Both Way RTP Media | |<==========================>| | | |re-INVITE F5 re-INVITE F6 | |------------ -------------| Hasebe [Page 23] Internet Draft Exceptional Procedure Examples Jul 8th,2005 | \ / | | X | | / \ | |<----------- ------------>| | 491 F8 491 F7 | |------------ -------------| | \ / | | X | | / \ | |<----------- ------------>| | ^ ACK F9 ^ ACK F10| |--|--------- ----|--------| | | \ / | | | | X | | | | / \ | | |<-|---------- ---|------->| | | | | | |0-2.0 sec | | | | | | | v re-INVITE F11 | | |<------------------|--------| | 200 OK F12 | | |-------------------|------->| | ACK F13 | | |<------------------|--------| | | | | |2.1-4.0 sec | | | | re-INVITE F14 v | |--------------------------->| | 200 OK F15 | |<---------------------------| | ACK F16 | |--------------------------->| | | | | In this scenario, Alice and Bob send a re-INVITE at the same time. When two re-INVITEs cross in the same dialog, it sends after different intervals.(RFC3261,14.1) When Alice sends an initial INVITE, an INVITE will be sent again after 2.1-4.0 seconds because she generated the Call-ID (owner of the Call-ID). Bob will send an INVITE again after 0.0-2.0 seconds, because Bob isn't the owner of the Call-ID. Therefore, each user agent must remember whether they has generated the Call-ID of the dialog or not, because an INVITE may be crossed by another INVITE. Message Details Hasebe [Page 24] Internet Draft Exceptional Procedure Examples Jul 8th,2005 F1 INVITE Alice -> Bob INVITE sip:bob@biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 Supported: timer Session-Expires: 300 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: 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/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: Content-Length: 0 F3 200 OK Bob -> Alice SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Require: timer Session-Expires: 300;refresher=uas From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: Content-Type: application/sdp Hasebe [Page 25] Internet Draft Exceptional Procedure Examples Jul 8th,2005 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/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 ACK Content-Length: 0 /* RTP streams are established between Alice and Bob */ F5 re-INVITE Alice -> Bob INVITE sip:sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 2 INVITE Content-Length: 151 v=0 o=alice 2890844526 2890844527 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 a=sendonly F6 re-INVITE Bob -> Alice INVITE sip:alice@client.atlanta.example.com SIP/2.0 Via: SIP/2.0/UDP client.biloxi.example.com:5060;branch=z9hG4bKnashds7 Hasebe [Page 26] Internet Draft Exceptional Procedure Examples Jul 8th,2005 Session-Expires: 300;refresher=uac Max-Forwards: 70 From: Bob ;tag=8321234356 To: Alice ;tag=9fxced76sl Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Content-Length: 0 /* A case where a re-INVITE for a session refresh and a re-INVITE for hold are sent at the same time.*/ F7 491 Request Pending Bob -> Alice SIP/2.0 491 Request Pending Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 2 INVITE Content-Length: 0 /*Since an INVITE is processing, a 491 response are returned.*/ F8 491 Request Pending Alice -> Bob SIP/2.0 491 Request Pending Via: SIP/2.0/UDP client.biloxi.example.com:5060;branch=z9hG4bKnashds7 From: Bob ;tag=8321234356 To: Alice ;tag=9fxced76sl Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Content-Length: 0 F9 ACK(INVITE) Alice -> Bob ACK sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.biloxi.example.com:5060;branch=z9hG4bKnashds7 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 2 ACK Content-Length: 0 F10 ACK(INVITE) Alice -> Bob ACK sip:bob@client.biloxi.example.com SIP/2.0 Hasebe [Page 27] Internet Draft Exceptional Procedure Examples Jul 8th,2005 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 From: Bob ;tag=8321234356 To: Alice ;tag=9fxced76sl Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 ACK Content-Length: 0 F11 re-INVITE Bob -> Alice INVITE sip:alice@client.atlanta.example.com SIP/2.0 Via: SIP/2.0/UDP client.biloxi.example.com:5060;branch=z9hG4bKnashds7.1 Session-Expires: 300;refresher=uac Max-Forwards: 70 From: Bob ;tag=8321234356 To: Alice ;tag=9fxced76sl Call-ID: 3848276298220188511@atlanta.example.com CSeq: 2 INVITE Content-Length: 0 /*Since Bob is not the owner of Call-ID, Bob send again the INVITE after 0.0-2.0 seconds. */ F12 200 OK Alice -> Bob SIP/2.0 200 OK Via: SIP/2.0/UDP client.biloxi.example.com:5060;branch=z9hG4bKnashds7.1 Session-Expires: 300;refresher=uac Max-Forwards: 70 From: Bob ;tag=8321234356 To: Alice ;tag=9fxced76sl Call-ID: 3848276298220188511@atlanta.example.com CSeq: 2 INVITE Content-Length: 0 F13 ACK Bob -> Alice ACK sip:alice@client.atlanta.example.com SIP/2.0 Via: SIP/2.0/UDP client.biloxi.example.com:5060;branch=z9hG4bK74b44 Session-Expires: 300;refresher=uac Max-Forwards: 70 From: Bob ;tag=8321234356 To: Alice ;tag=9fxced76sl Call-ID: 3848276298220188511@atlanta.example.com CSeq: 2 ACK Content-Length: 0 Hasebe [Page 28] Internet Draft Exceptional Procedure Examples Jul 8th,2005 F14 re-INVITE Alice -> Bob INVITE sip:sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9.1 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 3 INVITE Content-Length: 151 v=0 o=alice 2890844526 2890844527 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 a=sendonly /*Since Alice is the owner of Call-ID, Alice send again the INVITE after 2.1-4.0 seconds. */ F15 200 OK Bob -> Alice SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9.1 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 3 INVITE Content-Length: 151 v=0 o=bob 2890844527 2890844528 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 a=recvonly F16 ACK Alice -> Bob ACK sip:sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK230f2.1 Max-Forwards: 70 Hasebe [Page 29] Internet Draft Exceptional Procedure Examples Jul 8th,2005 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 3 ACK Content-Length: 0 2.7. Initial INVITE retransmission Alice Bob | | | ini-INVITE F1 | |------------------------------->| | 180 F2(Packet loss) | | X<---------------------| | | | ini-INVITE F4 200 F3 | |------------- --------------| Terminate(ServerTransaction) | \ / | | X | | / \ | |<------------ ------------->| | ACK F5 | |------------------------------->| | | | | In this scenario, all provisional responses to the initial INVITE (ini-INVITE) are lost, and a UAC retransmits an ini-INVITE. At the same time as retransmission, a UAS generates a 200 OK to the ini-INVITE and it terminate an INVITE server transaction. (RFC3261,13.3.1.4) After sending a 200 OK, a TU of UAS processes ACK and retransmission of 200 OK.(RFC3261,17.1) A TU of UAS processes a retransmited ini-INVITE, but it doesn't have a To-tag, therefore the TU cannot use a mechanism to recognize the dialog by From-tag, Call-ID and To-tag. However, it must recognize correctly a retransmited ini-INVITE by From-tag and Call-ID. (It must not construct a new dialog for a retransmited ini-INVITE as a request outside dialog.) Since a TU of UAS retransmit a 200 OK by the timer of the waiting for ACK, it isn't necessary to retransmit 200 OK to retransmited ini-INVITE. Message Details F1 INVITE Alice -> Bob INVITE sip:bob@biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 Hasebe [Page 30] Internet Draft Exceptional Procedure Examples Jul 8th,2005 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: 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/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: Content-Length: 0 /*A 180 response is lost and does not arrive to Alice.*/ F3 200 OK Bob -> Alice SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: 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 Hasebe [Page 31] Internet Draft Exceptional Procedure Examples Jul 8th,2005 t=0 0 m=audio 3456 RTP/AVP 0 a=rtpmap:0 PCMU/8000 /* Bob sends a 200 OK and terminates the INVITE transaction at the same time. TU performs retransmitting of a 200 OK directly.*/ F4 INVITE(retransmission) Alice -> Bob INVITE sip:bob@biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: 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 /*Since F2 is lost, Alice retransmits an ini-INVITE. The retransmited INVITE does not match any existing transaction because Bob has already sent a 200 OK. Moreover, the retransmited ini-INVITE does not have a To-tag, so it doesn't match any existing dialog. Therefore, Bob have to recognize the retransmited INVITE correctly, without treating with the new INVITE.*/ F5 ACK Alice -> Bob ACK sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 ACK Content-Length: 0 2.8. Early Dialog Hasebe [Page 32] Internet Draft Exceptional Procedure Examples Jul 8th,2005 Alice Proxy Bob Carol | | | | | INVITE(sdp1) F1 | | | |--------------------->| INVITE(sdp1) F2 | | | 100 Trying F3 |--------------------->| | |<---------------------| 183(sdp2)To-tag=1 F4 | | | 183(sdp2)To-tag=1 F5 |<---------------------| | |<---------------------| | | | PRACK F6 | | | |--------------------->| PRACK F7 | | | |--------------------->| | | | 200(PRACK) F8 | | | 200(PRACK) F9 |<---------------------| | |<---------------------| | | |<=============Both Way RTP Media============>| | | | CANCEL F10 | | | |--------------------->| | | | 200(CANCEL) F11 | | | |<---------------------| | | | 487(INVITE) F12 | | | |<---------------------| | | | ACK(INVITE) F13 | | | |--------------------->| | | | | | | | | | | INVITE(sdp1) F14 | | |---------------------------->| | | 180 To-tag=2 F15 | | 180 To-tag=2 F16 |<----------------------------| |<---------------------| | | | 200(sdp3)To-tag=2 F17 | | 200(sdp3)To-tag=2 F18|<----------------------------| |<---------------------| | | ACK F19 | | |--------------------->| ACK F20 | | |---------------------------->| |<================Both Way RTP Media================>| | | | | | | In this scenario, a proxy is forking to another address (Carol), when Bob don't return final response. When a proxy sends INVITE to two or more addresses, two or more early dialogs may be formed in a UAC(Alice). The UAC terminates all existing early dialogs when it receives the final response to the ini-INVITE.(RFC3261,13.2.2.4) Only the confirmed dialog continues after a 200 OK reception. If Bob is replaced with a Media Server, you have the result appear to UAC just as this call flow. In this sequence, when Bob receives CANCEL, Hasebe [Page 33] Internet Draft Exceptional Procedure Examples Jul 8th,2005 it can terminate early media, but Alice does not know whether she should terminate an early media. When Bob stops sending RTP after receiving the CANCEL from the proxy, it seems to Alice that RTP broke off suddenly. Message Details F1 INVITE Alice -> Proxy INVITE sip:bob@biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Contact: Supported: 100rel 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 INVITE Proxy -> Bob INVITE sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK721e.1 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Max-Forwards: 69 Record-Route: From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Contact: Supported: 100rel Content-Type: application/sdp Content-Length: 151 v=0 o=alice 2890844526 2890844526 IN IP4 client.atlanta.example.com s=- Hasebe [Page 34] Internet Draft Exceptional Procedure Examples Jul 8th,2005 c=IN IP4 192.0.2.101 t=0 0 m=audio 49172 RTP/AVP 0 a=rtpmap:0 PCMU/8000 F3 100 Trying Proxy -> Alice SIP/2.0 100 Trying Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Content-Length: 0 F4 183 Session Progress Bob -> Proxy SIP/2.0 183 Session Progress Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK721e.1 ;received=192.0.2.233 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Record-Route: From: Alice ;tag=9fxced76sl To: Bob ;tag=314159 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Contact: Require: 100rel Content-Type: application/sdp Content-Length: 148 v=0 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com s=- c=IN IP4 192.0.2.100 t=0 0 m=audio 3456 RTP/AVP 0 a=rtpmap:0 PCMU/8000 F5 183 Session Progress Proxy -> Alice SIP/2.0 183 Session Progress Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Record-Route: Hasebe [Page 35] Internet Draft Exceptional Procedure Examples Jul 8th,2005 From: Alice ;tag=9fxced76sl To: Bob ;tag=314159 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE RSeq: 1 Contact: Require: 100rel Content-Type: application/sdp Content-Length: 148 v=0 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com s=- c=IN IP4 192.0.2.100 t=0 0 m=audio 3456 RTP/AVP 0 a=rtpmap:0 PCMU/8000 /*Early dialog is established between Alice and Bob,and early media is also established at the same time.*/ F6 PRACK Alice -> Proxy PRACK sip:bob@biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 Route: From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 2 PRACK RAck: 1 1 INVITE Content-Length: 0 F7 PRACK Proxy -> Bob PRACK sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK721e.2 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 2 PRACK RAck: 1 1 INVITE Content-Length: 0 F8 200 OK(PRACK) Bob -> Proxy Hasebe [Page 36] Internet Draft Exceptional Procedure Examples Jul 8th,2005 SIP/2.0 200 OK Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK721e.2 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 From: Alice ;tag=9fxced76sl To: Bob ;tag=314159 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 2 PRACK Contact: Content-Length: 0 F9 200 OK(PRACK) Proxy -> Alice SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 2 PRACK Content-Length: 0 F10 CANCEL Proxy -> Bob CANCEL sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK721e.2 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 CANCEL Content-Length: 0 /* The proxy cancels the INVITE to Bob, and sends an INVITE to Carol. Although the continuation of early media after CANCEL reception depends on the implementation of the user agent, Alice does not know that the proxy cancels the INVITE, therefore, when Bob stops the early media after the receiving a CANCEL, she think that the sound has stopped suddenly.*/ F11 200 OK(CANCEL) Bob -> Proxy SIP/2.0 200 OK Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK721e.2 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 CANCEL Content-Length: 0 Hasebe [Page 37] Internet Draft Exceptional Procedure Examples Jul 8th,2005 F12 487 Request Terminated(INVITE) Bob -> Proxy SIP/2.0 487 Request Terminated Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK721e.1 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;tag=314159 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Content-Length: 0 F13 ACK(INVITE) Proxy -> Bob ACK sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK721e.1 From: Alice ;tag=9fxced76sl To: Bob ;tag=314159 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 ACK Content-Length: 0 F14 INVITE Proxy -> Carol INVITE sip:carol@client.chicago.example.com SIP/2.0 Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK83749a.1 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Max-Forwards: 69 Record-Route: From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Contact: Supported: 100rel 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 Hasebe [Page 38] Internet Draft Exceptional Procedure Examples Jul 8th,2005 F15 180 Ringing Carol -> Proxy SIP/2.0 180 Ringing Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK83749a.1 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Record-Route: From: Alice ;tag=9fxced76sl To: Bob ;tag=456654 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Contact: Content Length:0 F16 180 Ringing Proxy -> Alice SIP/2.0 180 Ringing Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Record-Route: From: Alice ;tag=9fxced76sl To: Bob ;tag=456654 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Contact: Content Length:0 /*The proxy and Alice establish the second early dialog on receipt of a 180 response from Carol.*/ F17 200 OK Carol -> Proxy SIP/2.0 200 OK Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK83749a.1 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Record-Route: From: Alice ;tag=9fxced76sl To: Bob ;tag=456654 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Contact: Content Length: 151 v=0 o=carol 2890844922 2890844922 IN IP4 client.chicago.example.com s=Session SDP c=IN IP4 client.chicago.example.com Hasebe [Page 39] Internet Draft Exceptional Procedure Examples Jul 8th,2005 t=3034423619 0 m=audio 3456 RTP/AVP 0 a=rtpmap:0 PCMU/8000 F18 200 OK Proxy -> Alice SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Record-Route: From: Alice ;tag=9fxced76sl To: Bob ;tag=456654 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Contact: Content Length: 151 v=0 o=carol 2890844922 2890844922 IN IP4 client.chicago.example.com s=Session SDP c=IN IP4 client.chicago.example.com t=3034423619 0 m=audio 3456 RTP/AVP 0 a=rtpmap:0 PCMU/8000 /* On receipt of a 200 OK response, all existing early dialogs except what been confirmed are terminated.*/ F19 ACK Alice -> Proxy ACK sip:carol@client.chicago.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bq9 Max-Forwards: 70 Route: From: Alice ;tag=9fxced76sl To: Bob ;tag=456654 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 ACK Content-Length: 0 F20 ACK Proxy -> Carol ACK sip:carol@client.chicago.example.com SIP/2.0 Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK721e.1 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bq9 ;received=192.0.2.101 Max-Forwards: 69 Hasebe [Page 40] Internet Draft Exceptional Procedure Examples Jul 8th,2005 From: Alice ;tag=9fxced76sl To: Bob ;tag=456654 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 ACK Content-Length: 0 2.9. CANCEL crossover via a stateful proxy Alice Proxy Bob | | | | INVITE F1 | | |--------------------->| INVITE F2 | | 100 Trying F3 |--------------------->| |<---------------------| 180 Ringing F4 | | 180 F5 |<---------------------| |<---------------------| | | | | | CANCEL F6 | | |--------------------->| CANCEL F7 200 F8 | | 200(CANCEL) F9 |--------- --------| |<---------------------| \ / | | | X | | | / \ | | 200(INVITE) F10 |<-------- ------->| |<---------------------| 481(CANCEL) F11 | | ACK F12 |<---------------------| |--------------------->| ACK F13 | | |--------------------->| | BYE F14 | | |--------------------->| BYE F15 | | |--------------------->| | | 200 F16 | | 200 F17 |<---------------------| |<---------------------| | | | | | | | If a CANCEL crosses a 200 OK to an INVITE between Bob and a stateful proxy, the UAC may receive a 200 OK to the INVITE after receiving 200 OK to the CANCEL. TU must manage a CANCEL transaction and an INVITE transaction independently, and even if a CANCEL is successful, TU cannot terminate an INVITE transaction, as described on 9.1 of RFC3261. Like a CANCEL crossover of 2.1, the UAC may send a BYE and terminate the session immediately after receiving 200 OK to an INVITE. Message Details Hasebe [Page 41] Internet Draft Exceptional Procedure Examples Jul 8th,2005 F1 INVITE Alice -> Proxy INVITE sip:bob@biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 Max-Forwards: 70 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Contact: 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 INVITE Proxy -> Bob INVITE sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK721e.1 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Max-Forwards: 69 Record-Route: From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Contact: 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 F3 100 Trying Proxy -> Alice SIP/2.0 100 Trying Hasebe [Page 42] Internet Draft Exceptional Procedure Examples Jul 8th,2005 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Content-Length: 0 F4 180 Ringing Bob -> Proxy SIP/2.0 180 Ringing Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK721e.1 ;received=192.0.2.233 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Record-Route: From: Alice ;tag=9fxced76sl To: Bob ;tag=314159 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Contact: Content-Length: 0 F5 180 Ringing Proxy -> Alice SIP/2.0 180 Ringing Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Record-Route: From: Alice ;tag=9fxced76sl To: Bob ;tag=314159 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Contact: Content-Length: 0 F6 CANCEL Alice -> Proxy CANCEL sip:bob@biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 CANCEL Content-Length: 0 Hasebe [Page 43] Internet Draft Exceptional Procedure Examples Jul 8th,2005 F7 CANCEL Proxy -> Bob CANCEL sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK721e.2 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 CANCEL Content-Length: 0 /* Proxy sent a 200 OK to the CANCEL and Bob sent INVITE at the same time.*/ F8 200 OK(INVITE) Bob -> Proxy SIP/2.0 200 OK Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK721e.1 ;received=192.0.2.233 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Record-Route: From: Alice ;tag=9fxced76sl To: Bob ;tag=314159 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Contact: Content-Type: application/sdp Content-Length: 148 v=0 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com s=- c=IN IP4 192.0.2.100 t=0 0 m=audio 3456 RTP/AVP 0 a=rtpmap:0 PCMU/8000 F9 200 OK(CANCEL) Proxy -> Alice SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 CANCEL Content-Length: 0 /* Since CANCEL requests are hop-by-hop, the proxy answers with a 200 OK Hasebe [Page 44] Internet Draft Exceptional Procedure Examples Jul 8th,2005 to the CANCEL of Alice. Note that the 200 OK doesn't mean the success of the CANCEL to the INVITE.*/ F10 200 OK(INVITE) Proxy -> Alice SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bf9 ;received=192.0.2.101 Record-Route: From: Alice ;tag=9fxced76sl To: Bob ;tag=314159 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 INVITE Contact: Content-Type: application/sdp Content-Length: 148 v=0 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com s=- c=IN IP4 192.0.2.100 t=0 0 m=audio 3456 RTP/AVP 0 a=rtpmap:0 PCMU/8000 F11 481 Call/Transaction Does Not Exist Bob -> Proxy SIP/2.0 481 Call/Transaction Does Not Exist Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK721e.2 From: Alice ;tag=9fxced76sl To: Bob Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 CANCEL Content-Length: 0 /* Since Bob has already sent 200 OK to INVITE, CANCEL fails with 481 response.*/ F12 ACK Alice -> Proxy ACK sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bq9 Max-Forwards: 70 Route: From: Alice ;tag=9fxced76sl To: Bob ;tag=314159 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com Hasebe [Page 45] Internet Draft Exceptional Procedure Examples Jul 8th,2005 CSeq: 1 ACK Content-Length: 0 F13 ACK Proxy -> Bob ACK sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK721e.1 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74bq9 ;received=192.0.2.101 Max-Forwards: 69 From: Alice ;tag=9fxced76sl To: Bob ;tag=314159 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 1 ACK Content-Length: 0 F14 BYE Alice -> Proxy BYE sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74be5 Max-Forwards: 70 Route: From: Alice ;tag=9fxced76sl To: Bob ;tag=314159 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 2 BYE Content-Length: 0 /* Alice may send a BYE and terminate the sessin immediately on receipt of a 200 OK after the CANCEL.*/ F15 BYE Proxy -> Bob BYE sip:bob@client.biloxi.example.com SIP/2.0 Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK739578.1 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74be5 ;received=192.0.2.101 Max-Forwards: 69 From: Alice ;tag=9fxced76sl To: Bob ;tag=314159 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 2 BYE Content-Length: 0 F16 200 OK Bob -> Proxy Hasebe [Page 46] Internet Draft Exceptional Procedure Examples Jul 8th,2005 SIP/2.0 200 OK Via: SIP/2.0/UDP ss.atlanta.example.com:5060;branch=z9hG4bK739578.1 Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74be5 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;tag=314159 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 2 BYE Content-Length: 0 F17 200 OK Proxy -> Alice SIP/2.0 200 OK Via: SIP/2.0/UDP client.atlanta.example.com:5060;branch=z9hG4bK74be5 ;received=192.0.2.101 From: Alice ;tag=9fxced76sl To: Bob ;tag=314159 Call-ID: 2xTb9vxSit55XU7p8@atlanta.example.com CSeq: 2 BYE Content-Length: 0 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. [6] Rosenberg, J. and H. Schulzrinne, "Reliability of Provisional Responses in the Session Initiation Protocol (SIP)", RFC 3262, June 2002. 4. Intellectual Property Statement Hasebe [Page 47] Internet Draft Exceptional Procedure Examples Jul 8th,2005 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 Hasebe [Page 48] Internet Draft Exceptional Procedure Examples Jul 8th,2005 19-2 Nishi-shinjuku 3-chome Shinjuku-ku Tokyo 163-8019 Japan EMail: tomoyuki.yoshikawa@rdc.east.ntt.co.jp 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 Hasebe [Page 49] Internet Draft Exceptional Procedure Examples Jul 8th,2005 Funding for the RFC Editor function is currently provided by the Internet Society. The Expiration date for this Internet Draft is: August 14th, 2005 Hasebe [Page 50]