1、 9.2.1 International Telecommunication Union ITU-T V.153TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (12/2009) SERIES V: DATA COMMUNICATION OVER THE TELEPHONE NETWORK Interworking with other networks Interworking between ITU-T T.38 and ITU-T V.152 using IP peering for real-time facsimile services
2、 Recommendation ITU-T V.153 ITU-T V-SERIES RECOMMENDATIONS DATA COMMUNICATION OVER THE TELEPHONE NETWORK General V.1V.9 Interfaces and voiceband modems V.10V.34 Wideband modems V.35V.39 Error control V.40V.49 Transmission quality and maintenance V.50V.59 Simultaneous transmission of data and other s
3、ignals V.60V.99 Interworking with other networks V.100V.199Interface layer specifications for data communication V.200V.249 Control procedures V.250V.299 Modems on digital circuits V.300V.399 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T V.153 (12/2009) i Recomme
4、ndation ITU-T V.153 Interworking between ITU-T T.38 and ITU-T V.152 using IP peering for real-time facsimile services Summary Recommendation ITU-T V.153 defines service interworking between two IP domains, whereby one IP domain is using voiceband data over IP (VBDoIP) transport according to Recommen
5、dation ITU-T V.152 and the other IP domain is using facsimile relay over IP (FoIP) transport according to Recommendation ITU-T T.38. Two modes of operation are specified for the T.38-to-V.152 interworking function: native versus emulated interworking. The T.38-to-V.152 interworking technology is sub
6、ject of the user plane and typically located in IP-to-IP gateway equipment, like border routers or border gateways. History Edition Recommendation Approval Study Group 1.0 ITU-T V.153 2009-12-14 16 ii Rec. ITU-T V.153 (12/2009) FOREWORD The International Telecommunication Union (ITU) is the United N
7、ations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendatio
8、ns on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval
9、 of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“
10、 is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g., interoperability or applicability) and compliance wi
11、th the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is requir
12、ed of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectu
13、al Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. Howe
14、ver, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2010 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the pr
15、ior written permission of ITU. Rec. ITU-T V.153 (12/2009) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 3 5 Conventions 4 6 Overview 4 7 Definition of the principal modes of operatio
16、n . 5 7.1 Emulation mode 5 7.2 Native mode 6 7.3 Methods for discrimination between native and emulation mode 6 8 Interworking function: Specific items for consideration 7 8.1 ITU-T T.30 procedures . 7 8.2 Data rate management for ITU-T V.34 facsimile 7 9 Capability negotiation/determination for V.1
17、52-to-T.38 interworking 7 9.1 General . 7 9.2 Negotiation using SDP . 8 10 Handling of stimuli between VBDoIP and FoIP 9 11 Synchronization of state transitioning between VBDoIP and FoIP state machines . 10 Appendix I Performance evaluation of both modes of operation . 11 I.1 Gateway transfer delay
18、. 11 I.2 Gateway transfer delay variation 11 I.3 Gateway information loss . 12 I.4 Dejitter buffer aspects . 12 I.5 Aspect of redundant packet transport . 12 Appendix II H.248 bearer establishment procedure examples . 13 II.1 Introduction 13 II.2 MG state transitioning: MGC-strict controlled method
19、versus MG autonomous transitioning . 13 II.3 Example network model . 13 II.4 Example signalling . 15 Bibliography. 23 Rec. ITU-T V.153 (12/2009) 1 Recommendation ITU-T V.153 Interworking between ITU-T T.38 and ITU-T V.152 using IP peering for real-time facsimile services 1 Scope ITU-T V.152 describe
20、s the voiceband data (VBD) operation of voice-over-Internet protocol (VoIP) gateways, which may be abbreviated as VBDoIP. ITU-T T.38 describes the facsimile packet relay operation of voice-over-Internet protocol (VoIP) gateways, which may be abbreviated as FoIP. Both these gateway models consider ex
21、plicitly interworking between an IP-based packet-switched network on one side and a circuit-switched network on the other side. This Recommendation describes procedures for direct service interworking (according to the definition in clause 3.2 of ITU-T Y.1251) of two IP domains, whereby one IP domai
22、n uses V.152-based VBDoIP transport and the other IP domain uses T.38-based FoIP transport. The term voiceband data is an umbrella term for all kinds of teleservices that use a “data-oriented transport“ in the frequency band of the narrow-band voice spectrum (which is a 3.1-kHz-band). The data-orien
23、ted transport is realized by modem protocols (the definition for modem can be found in clause 3.13 of ITU-T V.152), as defined, e.g., within the ITU-T V-series Recommendations. Teleservices may be categorized into three major applications areas: facsimile, text-based communication and general data s
24、ervices. The three VBD application areas may be summarized as (by using notation “application/transport“): Facsimile/modem: Gateway technologies for PSTN-to-IP interworking, see, e.g., ITU-T V.152 for pass-through mode and ITU-T T.38 for packet relay mode. Text/modem: Gateway technologies for PSTN-t
25、o-IP interworking, see, e.g., ITU-T V.152 for pass-through mode and b-ITU-T V.151 for packet relay mode. Data/modem: Gateway technologies for PSTN-to-IP interworking, see, e.g., ITU-T V.152 for pass-through mode and b-ITU-T V.150.1 for packet relay mode. This Recommendation only considers facsimile/
26、modem. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to
27、revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within
28、this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T H.245 Recommendation ITU-T H.245 (2008), Control protocol for multimedia communication. ITU-T H.248.1 Recommendation ITU-T H.248.1 (2005), Gateway Control Protocol: Version 3, including its Amendme
29、nt 2 (2009). ITU-T H.323 Recommendation ITU-T H.323 (2006), Packet-based multimedia communications systems. 2 Rec. ITU-T V.153 (12/2009) ITU-T Q.3303.2 Recommendation ITU-T Q.3303.2 (2007), Resource control protocol No. 3 Protocol at the interface between a Policy Decision Physical Entity (PD-PE) an
30、d a Policy Enforcement Physical Entity (PE-PE) (Rw interface): H.248 alternative. ITU-T T.30 Recommendation ITU-T T.30 (2005), Procedures for document facsimile transmission in the general switched telephone network. ITU-T T.38 Recommendation ITU-T T.38 (2007), Procedures for real-time Group 3 facsi
31、mile communication over IP networks. ITU-T V.152 Recommendation ITU-T V.152 (2005), Procedures for supporting voice-band data over IP networks, and its Corrigenda 1 (2005) and 2 (2006). ITU-T Y.1251 Recommendation ITU-T Y.1251 (2002), General architectural model for interworking. IETF RFC 2198 IETF
32、RFC 2198 (1997), RTP Payload for Redundant Audio Data. IETF RFC 2733 IETF RFC 2733 (1999), An RTP Payload Format for Generic Forward Error Correction. IETF RFC 3261 IETF RFC 3261 (2002), SIP: Session Initiation Protocol. IETF RFC 3550 IETF RFC 3550 (2003), RTP: A Transport Protocol for Real-Time App
33、lications. IETF RFC 3551 IETF RFC 3551 (2003), RTP Profile for Audio and Video Conferences with Minimal Control. IETF RFC 4566 IETF RFC 4566 (2006), SDP: Session Description Protocol. IETF RFC 4733 IETF RFC 4733 (2006), RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals. 3 Definition
34、s 3.1 Terms defined elsewhere The terms defined in clause 3 of ITU-T V.152 and clause 3 of ITU-T T.38 are applicable, as far as relevant, in this Recommendation. In addition: 3.1.1 voiceband data b-ITU-T V.150.0: The transport of modem signals over a voice channel of a packet network with the encodi
35、ng appropriate for modem signals. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 emulated VBDoIP-to-FoIP mode: This is an internal mode of operation of the VBDoIP-to-FoIP gateway with an indirect interworking between both IP connection endpoints. This
36、 is done using a gateway that embeds internal TDM-based, 64-kbit/s bearer channels. The two (gateway local) IP connection endpoints do thus represent emulated ITU-T V.152 and ITU-T T.38 gateway functions. 3.2.2 facsimile packet relay mode (“fax relay“ for short): The transport of facsimile/modem dat
37、a across an IP-based packet network using ITU-T T.38. 3.2.3 IP peering: IP peering denotes the interconnection of two IP domains (at the network protocol layer). Rec. ITU-T V.153 (12/2009) 3 3.2.4 native VBDoIP-to-FoIP mode: This is an internal mode of operation of the VBDoIP-to-FoIP gateway with a
38、direct interworking between both (gateway local) IP connection endpoints where no circuit-switched bearer technology is used internally in the gateway. 3.2.5 VBDoIP-to-FoIP gateway: A media gateway that is compliant with this Recommendation. 3.2.6 voiceband data mode adapted from ITU-T V.152: VBDoIP
39、 is the transport of voiceband data over a voice channel of an IP-based packet network with the encoding appropriate for modem signals as defined in ITU-T V.152, clause 6. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: B2BUA (SIP) Back-to-Back User Ag
40、ent BICC Bearer Independent Call Control CSN Circuit-Switched Network DS0 Digital Signal level 0 FoIP Facsimile-over-IP FoTDM Facsimile-over-TDM G3FE Group 3 Facsimile Equipment GSTN General Switched Telephone Network IMS IP Multimedia System IP Internet Protocol IPDV IP Packet Delay Variation IPLR
41、IP Packet Loss Ratio IPTD IP Packet Transfer Delay ISDN Integrated Services Digital Network IWF Interworking Function MG Media Gateway MGC Media Gateway Controller NGN Next Generation Network NTE Network Telephone Event O/A (SDP) Offer/Answer PE-PE Policy Enforcement Physical Entity PES PSTN Emulati
42、on Subsystem PSTN Public Switched Telephone Network PT (RTP) Payload Type/Packet Type RTCP RTP Control Protocol RTP Real-time Transport Protocol SDP Session Description Protocol SIP Session Initiation Protocol 4 Rec. ITU-T V.153 (12/2009) SLA Service Level Agreement (S)TDM (Synchronous) Time Divisio
43、n Multiplexing TPKT Transport Protocol Data Unit Packet UA (SIP) User Agent UDP User Datagram Protocol UDPTL Facsimile UDP Transport Layer (protocol) VBD Voiceband Data VBDoIP Voiceband Data-over-IP VBDoTDM Voiceband Data-over-TDM 5 Conventions None. 6 Overview This Recommendation considers real-tim
44、e facsimile services in case of IP peering. The understanding of IP peering is here simplified to the peer model of an ITU-T T.38 domain (“FoIP“ for fax-over-IP) with an ITU-T V.152 domain (“VBDoIP“ for voiceband data-over-IP). Figure 1 recalls again the two interworking models of ITU-T T.38 and ITU
45、-T V.152. Figure 1 Interworking between CSN and IP networks using T.38-to-T.38 and V.152-to-V.152 topologies Both models consider explicitly interworking between an IP network on one side and a circuit-switched network (CSN) on the other side: ITU-T V.152: VBDoIP for PSTN-to-IP interworking. ITU-T T
46、.38: FoIP for GSTN-to-IP interworking. That means that an ITU-T V.152 gateway and an ITU-T T.38 gateway always have an IP interface and either an analogue line interface, or a digital 1 x 64 kbit/s synchronous TDM (STDM) interface. In this Recommendation, “IP peering“ denotes the interconnection of
47、two IP domains (at the network protocol layer). FoIP (Media) GatewayT.38:FoTDM-to-FoIPInterworking FunctionEmitting GatewayFoIP (Media) GatewayT.38:FoTDM-to-FoIPInterworking FunctionEmitting GatewayPSTN/GSTNDomainFoIP (Media) GatewayT.38:FoTDM-to-FoIPInterworking FunctionReceiving GatewayFoIP (Media
48、) GatewayT.38:FoTDM-to-FoIPInterworking FunctionReceiving GatewayIPDomainCalling TerminalCalled TerminalPSTN/GSTNDomainVBDoIP (Media) GatewayV.152:VBDoTDM-to-VBDoIPInterworking FunctionEmitting GatewayVBDoIP (Media) GatewayV.152:VBDoTDM-to-VBDoIPInterworking FunctionEmitting GatewayPSTN/GSTNDomainVB
49、DoIP (Media) GatewayV.152:VBDoTDM-to-VBDoIPInterworking FunctionReceiving GatewayVBDoIP (Media) GatewayV.152:VBDoTDM-to-VBDoIPInterworking FunctionReceiving GatewayIPDomainCalling TerminalCalled TerminalPSTN/GSTNDomain(1) T.38 model = circuit-to-IP gateways (2) V.152 model = circuit-to-IP gateways Rec. ITU-T V.153 (12/2009) 5 Each IP domain could support ITU-T V.152 only, or ITU-T T.38 only, or both, for the transport of real-time facsimile traffic.
