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 Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. 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) 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. Hasebe [Page 1] Internet Draft Semi Regular Examples Feb 14th,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. 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]. Hasebe [Page 2] Internet Draft Semi Regular Examples Feb 14th,2005 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. */ Hasebe [Page 3] Internet Draft Semi Regular Examples Feb 14th,2005 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. Hasebe [Page 4] Internet Draft Semi Regular Examples Feb 14th,2005 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. Hasebe [Page 5] Internet Draft Semi Regular Examples Feb 14th,2005 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 ;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/TCP 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@client.biloxi.example.com;transport=tcp SIP/2.0 Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 From: Alice ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 CANCEL Contact: 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 ;tag=9fxced76sl To: Bob ;tag=8321234356 Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: Content-Length: 0 Hasebe [Page 6] Internet Draft Semi Regular Examples Feb 14th,2005 /* 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 ;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/TCP 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 /* Bob has sent the final response, and a CANCEL becomes invalid. RTP streams are established.*/ Hasebe [Page 7] Internet Draft Semi Regular Examples Feb 14th,2005 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. Hasebe [Page 8] Internet Draft Semi Regular Examples Feb 14th,2005 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 ;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/TCP 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/TCP 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 Hasebe [Page 9] Internet Draft Semi Regular Examples Feb 14th,2005 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 ;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/TCP 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. */ Hasebe [Page 10] Internet Draft Semi Regular Examples Feb 14th,2005 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 ;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/TCP 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 Via: SIP/2.0/TCP 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. */ Hasebe [Page 11] Internet Draft Semi Regular Examples Feb 14th,2005 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. Hasebe [Page 12] Internet Draft Semi Regular Examples Feb 14th,2005 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 ;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/TCP 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 Hasebe [Page 13] Internet Draft Semi Regular Examples Feb 14th,2005 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 ;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 /* 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 ;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/TCP 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. */ Hasebe [Page 14] Internet Draft Semi Regular Examples Feb 14th,2005 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 ;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/TCP 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/TCP 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 Via: SIP/2.0/TCP 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: 1 INVITE Content-Length: 0 Hasebe [Page 15] Internet Draft Semi Regular Examples Feb 14th,2005 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 Semi Regular Examples Feb 14th,2005 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 ;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/TCP 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/TCP 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 17] Internet Draft Semi Regular Examples Feb 14th,2005 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 ;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/TCP 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 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 ;tag=8321234356 To: Alice ;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. */ Hasebe [Page 18] Internet Draft Semi Regular Examples Feb 14th,2005 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 ;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/TCP 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. */ Hasebe [Page 19] Internet Draft Semi Regular Examples Feb 14th,2005 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. Hasebe [Page 20] Internet Draft Semi Regular Examples Feb 14th,2005 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 ;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/TCP 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 Hasebe [Page 21] Internet Draft Semi Regular Examples Feb 14th,2005 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 ;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/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bd5 Supported: timer Session-Expires: 300 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) */ Hasebe [Page 22] Internet Draft Semi Regular Examples Feb 14th,2005 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 ;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/TCP 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 SIP/2.0 200 OK Via: SIP/2.0/TCP 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.*/ Hasebe [Page 23] Internet Draft Semi Regular Examples Feb 14th,2005 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 ;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.) */ 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] Internet Draft Semi Regular Examples Feb 14th,2005 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 Hasebe [Page 26] Internet Draft Semi Regular Examples Feb 14th,2005