1、 ETSI TR 183 056 V2.1.1 (2009-02) Technical Report Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); Feasibility study on new methods for Overlap Sending ETSI ETSI TR 183 056 V2.1.1 (2009-02) 2 Reference DTR/TISPAN-03111-NGN-R2 Keywords IMS, signallin
2、g ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre la Sous-Prfecture de Grasse (06) N 7803/88 Important notice Individual copies of the present document can
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5、ents is available at http:/portal.etsi.org/tb/status/status.asp If you find errors in the present document, please send your comment to one of the following services: http:/portal.etsi.org/chaircor/ETSI_support.asp Copyright Notification No part may be reproduced except as authorized by written perm
6、ission. The copyright and the foregoing restriction extend to reproduction in all media. European Telecommunications Standards Institute 2009. All rights reserved. DECTTM, PLUGTESTSTM, UMTSTM, TIPHONTM, the TIPHON logo and the ETSI logo are Trade Marks of ETSI registered for the benefit of its Membe
7、rs. 3GPPTM is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. LTE is a Trade Mark of ETSI currently being registered for the benefit of its Members and of the 3GPP Organizational Partners. GSM and the GSM logo are Trade Marks registered and own
8、ed by the GSM Association. ETSI ETSI TR 183 056 V2.1.1 (2009-02) 3 Contents Intellectual Property Rights5 Foreword.5 Introduction 5 1 Scope 6 2 References 6 2.1 Normative references .6 2.2 Informative references6 3 Definitions and abbreviations.7 3.1 Definitions7 3.2 Abbreviations .7 4 Requirements
9、and Issues 8 4.1 Requirements8 4.2 Issues 8 4.2.1 Routing related issues: 9 4.2.2 Interrelation with number portability9 4.2.3 Interrelation with the support of wildcard PUID 9 4.2.4 No IMS defined solutions .10 4.2.5 Overlap Scenarios supported 10 4.2.5.1 Overlap transit.10 4.2.5.2 Terminating over
10、lap10 4.2.5.3 Originating overlap (IMS PES).11 4.2.6 Different error responses for incomplete and unknown number.11 5 Overview of technical solutions.11 5.1 General .11 5.2 Mechanisms for the Reduction of Signalling Load 12 5.2.1 Provisioning of Number Length Information within Extension of the Erro
11、r-Info Field.12 5.2.1.1 Procedures.12 5.2.1.2 Encoding .14 5.2.2 Provisioning of Number Length Information within min/max Digit MIME body .15 5.2.2.1 Procedures.15 5.2.2.2 Encoding .15 5.2.3 Digit Collection at AGCF or VGW 16 5.2.4 Provisioning of Number Length Information within the SIP Reason head
12、er .16 5.2.4.1 Procedures.16 5.2.4.2 Encoding .16 5.3 Routeing Methods for Transmitting SIP networks.16 5.3.1 Overlap signalling using SIP in-dialog messages .16 5.3.2 Multiple INVITE method .17 5.3.2.1 Call ID Extended Routeing logic 17 5.3.2.2 Use of deterministic routeing configuration18 5.4 Inte
13、rworking.19 5.4.1 Interworking between in-dialog and multiple-INVITE methods19 5.4.1.1 General19 5.4.1.2 Call from network supporting the in-dialog method .19 5.4.1.3 Call from network supporting the multiple-INVITE method22 5.4.2 Interworking towards networks not supporting overlap signalling.25 5.
14、4.2.1 Forwarding overlap signalling and handling error responses from the network not supporting overlap in appropriate manner in originating network as specified in TS 129 163.25 6.4.2.2 Digit Collection in originating network and forwarding en-bloc signalling. 26 5.5 Impacts on other interfaces/no
15、des in the IMS network 26 5.5.1 I-CSCF Impacts 26 5.5.2 SLF .27 5.5.3 S-CSCF.27 ETSI ETSI TR 183 056 V2.1.1 (2009-02) 4 5.5.3.1 Originating 27 6 Comparison of solutions.28 6.1 Comparison of Signalling load reductions mechanisms.28 6.1.1 URL method (see clause 5.2)28 6.1.1.1 Pros .28 6.1.1.2 Cons 28
16、6.1.2 MIME method (see clause 5.3).28 6.1.2.1 Pros .28 6.1.2.2 Cons 28 6.1.3 Digit Collection at AGCF or VGW (see clause 5.2.3)29 6.1.3.1 Pros .29 6.1.3.2 Cons 29 6.1.4 Reason method (see clause 5.2.4).29 6.1.4.1 Pros .29 6.1.4.2 Cons 29 6.1.5 Conclusions.29 6.2 Comparison of Routeing mechanisms for
17、 Transmitting SIP networks 29 6.2.0 Comparison Criteria29 6.2.1 In Dialog method (see clause 5.5).30 6.2.2 Multiple INVITEs method (see clause 5.5 and related to clauses 5.2 and 5.3).31 6.3 Comparison of mechanisms for interworking towards networks not supporting overlap signalling32 6.3.1 Forwardin
18、g overlap signalling and handling error responses from the network not supporting overlap in appropriate manner in originating network.32 6.3.1.1 Pros .32 6.3.1.2 Cons 32 6.3.2 Digit Collection in originating network and forwarding en-bloc signalling. 32 6.3.2.1 Pros .32 6.3.2.2 Cons 32 6.4 Impacts
19、of inter-working between In-Dialog and Multi-INVITE overlap methods .32 7 Final Conclusion 33 Annex A: (network option): Call ID extended Overlap Dialling Procedures.34 A.1 Actions at the originating VGW/AGCF.34 A.1.1 Terminating overlap signalling at originating VGW/AGCF 34 A.1.2 Sending of INVITE
20、without determining the end of address signalling 35 A.1.3 Special handling of 404 Not Found and 484 Address Incomplete responses after sending of INVITE without determining the end of address signalling.36 A.2 Actions at the terminating VGW/AGCF 37 A.3 Timers.37 Annex B: Example calculation for sig
21、nalling load reduction as achieved by different proposals38 History 41 ETSI ETSI TR 183 056 V2.1.1 (2009-02) 5 Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is p
22、ublicly available for ETSI members and non-members, and can be found in ETSI SR 000 314: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on the E
23、TSI Web server (http:/webapp.etsi.org/IPR/home.asp). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which ar
24、e, or may be, or may become, essential to the present document. Foreword This Technical Report (TR) has been produced by ETSI Technical Committee Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN). Introduction The SIP protocol has been designed for ter
25、minal types that send the address information en-bloc rather than a digit at a time. Whilst this is not an issue for terminals such as PCs and mobile phones, this is an issue for stimulus mode terminals such as telephones. If the gateway controller that is controlling the access gateway for telephon
26、es, cannot determine the number length from the initial dialled digits, the procedures for an O-IWU described in ITU-T Recommendation Q.1912.5 i.4 and its ETSI endorsement are either to apply a timer to collect digits or to send an INVITE message with the digits collected so far to avoid call setup
27、delays due to this timer. If the INVITE contains incomplete digits, a SIP proxy in the session establishment path can return a SIP 404 “not found“ or SIP 484, Number Incomplete Message error response. For instance, the I-CSCF i.4 acting as entry point to the terminating IMS will return a 404 respons
28、e. An I-IWU as described in ITU-T Recommendation Q.1912.5 i.4 will return a SIP 484 error response. On receipt of the next digit the Gateway Controller may send a new INVITE with all the digits collected. If this is not enough then it will be rejected again along with sending the 484 or 404 message.
29、 This can be repeated digit by digit, with the session attempts progressing deeper and deeper into the network with the associated waste of signalling bandwidth and processing. The present document proposes a number of mechanisms that will help minimize these wasteful overheads without impacting on
30、the original mechanism and SIP. It also describes alternative mechanisms, one using SIP in-dialog messages, to transport the additional digits, once an early dialog has been established with the remote SIP entity. In addition, impacts to overlap routeing in SIP networks are also investigated. ETSI E
31、TSI TR 183 056 V2.1.1 (2009-02) 6 1 Scope The present document purpose is to investigate new methods for providing overlap sending originating from PSTN Networks and devices. The expectation is that such methods would save on processing that the present method for overlap sending deploys. It is also
32、 the aim of this investigation to be fully backward compatible, have no impact upon the SIP signalling protocols, and have a minimal impact upon the existing SIP nodes. 2 References References are either specific (identified by date of publication and/or edition number or version number) or non-spec
33、ific. For a specific reference, subsequent revisions do not apply. Non-specific reference may be made only to a complete document or a part thereof and only in the following cases: - if it is accepted that it will be possible to use all future changes of the referenced document for the purposes of t
34、he referring document; - for informative references. Referenced documents which are not found to be publicly available in the expected location might be found at http:/docbox.etsi.org/Reference. NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guar
35、antee their long term validity. 2.1 Normative references The following referenced documents are indispensable for the application of the present document. For dated references, only the edition cited applies. For non-specific references, the latest edition of the referenced document (including any a
36、mendments) applies. Not applicable. 2.2 Informative references The following referenced documents are not essential to the use of the present document but they assist the user with regard to a particular subject area. For non-specific references, the latest version of the referenced document (includ
37、ing any amendments) applies. i.1 ETSI ES 283 003: “Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); IP Multimedia Call Control Protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP) Stage 3 3GPP TS 24.229 (Release
38、7), modified“. i.2 IETF RFC 3261: “SIP: Session Initiation Protocol“. i.3 IETF RFC 3578: “Mapping of Integrated Services Digital Network (ISDN) User Part (ISUP) Overlap Signalling to the Session Initiation Protocol (SIP)“. i.4 ITU-T Recommendation Q.1912.5: “Interworking between Session Initiation P
39、rotocol (SIP) and Bearer Independent Call Control protocol or ISDN User Part“. i.5 ETSI TR 184 005: “Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); Types of numbers used in an NGN environment“. ETSI ETSI TR 183 056 V2.1.1 (2009-02) 7 i.6 ETSI TS 12
40、9 228: “Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); LTE; IP Multimedia (IM) Subsystem Cx and Dx Interfaces; Signalling flows and message contents (3GPP TS 29.228)“. i.7 ETSI TS 129 229: “Digital cellular telecommunications system (Phase 2
41、+); Universal Mobile Telecommunications System (UMTS); LTE; Cx and Dx interfaces based on Diameter protocol; Protocol details (3GPP TS 29.229)“. i.8 ETSI TS 129 163: “Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); LTE; Interworking between t
42、he IP Multimedia (IM) Core Network (CN) subsystem and Circuit Switched (CS) networks (3GPP TS 29.163)“. 3 Definitions and abbreviations 3.1 Definitions For the purposes of the present document, the following terms and definitions apply: deterministic routing: routeing method ensuring that subsequent
43、 INVITE requests for the same call are forwarded to the same next hop Incoming Interworking Unit (I-IWU): As defined in ITU-T Recommendation Q.1912.5 i.4. Outgoing Interworking Unit (O-IWU): As defined in ITU-T Recommendation Q.1912.5 i.4. 3.2 Abbreviations For the purposes of the present document,
44、the following abbreviations apply: ACK ACKnowledge AGCF Access Gateway Control Function AGW Access GateWay AS Application ServerB2BUA Back-to-Back User Agent BGCF Border Gateway Control Function BICC Bearer Independent Call Control CSCF Call Server Control Function DDI Direct Dialling In DNS Directo
45、ry Name Server DTMF Dual Tone Multi Frequency ENUM Electronic Number IAM Initial Address Message IBCF Interconnect Border Control Function I-CSCF Interrogating - CSCF ID IDentity IETF Internet Engineering Task Force I-IWU Incoming Interworking Unit IMS IP Multimedia Subsystem INFO Information messag
46、e ISUP ISDN User Part ITU-T International Telecommunications Union - Telephony MGC Media Gateway Controller MGCF Media Gateway Control Function MIME Multipurpose Internet Mail Extensions NICC Network Interoperability Consultative Committee O-IWU Outgoing Interworking Unit OS-IWF Overlap Signalling I
47、nterworking Function PBX Private PC Personal Computer ETSI ETSI TR 183 056 V2.1.1 (2009-02) 8 P-CSCF Proxy CSCF PES PSTN Emulation Subsystem PSTN Public Service Telephony Network PUID Public User Identity S-CSCF Serving CSCF SDP Service Description Protocol SIP Session Initiation Protocol SLF Server
48、 Local Function S-CSCF Service Call Server Control Function ST Signal Termination TrGW Trunking GateWay UAC User Agent Client UE User Equipment URI Uniform Resource Identifier VGW Voice Gateway XML eXtensible Markup Language 4 Requirements and Issues 4.1 Requirements 1) The use of the new overlap si
49、gnalling mechanism(s) minimize the additional signalling and processing load. 2) Any new overlap signalling mechanism is to be fully backward compatible with the overlap Release 1 SIP mechanism as described in RFC 3578 i.3. 3) The entities collecting digits within the IMS network should be able to distinguish between unknown and incomplete numbers. 4) Routeing Database requirements: - There needs to be a mechanism in the database to handle an incomplete string, and the means of signalling a unique response for a valid incomplete string. - S
