1、 ECMA-339 2ndEdition / December 2006 Corporate Telecommunication Networks Signalling Interworking between QSIG and SIP Basic Services Standard ECMA-339 2ndEdition / December 2006 Corporate Telecommunication Networks Signalling Interworking between QSIG and SIP Basic Services Ecma International Rue d
2、u Rhne 114 CH-1204 Geneva T/F: +41 22 849 6000/01 www.ecma-international.org IW ECMA-339.doc 06/12/2006 10:25 . Introduction This Standard is one of a series of Ecma Standards defining the interworking of services and signalling protocols deployed in corporate telecommunication networks (CNs) (also
3、known as enterprise networks). The series uses telecommunication concepts as developed by ITU-T and conforms to the framework of International Standards on Open Systems Interconnection as defined by ISO/IEC. This particular Standard defines the signalling protocol interworking for basic services bet
4、ween a Private Integrated Services Network (PISN) and a packet-based private telecommunications network based on the Internet Protocol (IP). It is further assumed that the protocol for the PISN part is QSIG and that the protocol for the IP-based network is SIP. Compared with the 1st edition, this 2n
5、d edition of this Ecma Standard includes numerous small changes arising during derived work in the IETF on RFC 4497. This 2nd edition is in full technical alignment with RFC 4497. This Standard is based upon the practical experience of Ecma member companies and the results of their active and contin
6、uous participation in the work of ISO/IEC JTC1, ITU-T, ETSI and other international and national standardization bodies. It represents a pragmatic and widely based consensus. This Ecma Standard has been adopted by the General Assembly of December 2006. Table of contents1 Scope 1 2 Conformance 1 3 Re
7、ferences 1 4 Terminology and Definitions 2 4.1 External Definitions 4.2 Other definitions 2 4.2.1 Corporate Telecommunication Network (CN) 4.2.2 Gateway 3 4.2.3 IP Network 3 4.2.4 Media Stream 3 4.2.5 Private Integrated Services Network (PISN) 4.2.6 Private Integrated Services Network Exchange (PINX
8、) 5 Acronyms 3 6 Background and Architecture 7 General Requirements 6 8 Message Mapping Requirements 8.1 Message Validation and Handling of Protocol Errors 8.2 Call Establishment from QSIG to SIP 7 8.2.1 Call Establishment from QSIG to SIP Using En Bloc Procedures 7 8.2.2 Call Establishment from QSI
9、G to SIP Using Overlap Procedures 9 8.3 Call Establishment from SIP to QSIG 11 8.3.1 Receipt of SIP INVITE Request for a New Call 11 8.3.2 Receipt of QSIG CALL PROCEEDING Message 12 8.3.3 Receipt of QSIG PROGRESS Message 12 8.3.4 Receipt of QSIG ALERTING Message 8.3.5 Inclusion of SDP Information in
10、 a SIP 18x Provisional Response 13 8.3.6 Receipt of QSIG CONNECT Message 13 8.3.7 Receipt of SIP PRACK Request 14 8.3.8 Receipt of SIP ACK Request 8.3.9 Receipt of a SIP INVITE Request for a Call Already Being Established 14 8.4 Call Clearing and Call Failure 15 8.4.1 Receipt of a QSIG DISCONNECT, R
11、ELEASE, or RELEASE COMPLETE Message 15 8.4.2 Receipt of a SIP BYE Request 16 - i - 8.4.3 Receipt of a SIP CANCEL Request 16 8.4.4 Receipt of a SIP 4xx-6xx Response to an INVITE Request 16 8.4.5 Gateway-Initiated Call Clearing 18 8.5 Request to Change Media Characteristics 18 9 Number Mapping 18 9.1
12、Mapping from QSIG to SIP 19 9.1.1 Using Information from the QSIG Called Party Number Information Element 19 9.1.2 Using Information from the QSIG Calling Party Number Information Element 19 9.1.3 Using Information from the QSIG Connected Number Information Element 19 9.2 Mapping from SIP to QSIG 20
13、 9.2.1 Generating the QSIG Called Party Number Information Element 20 9.2.2 Generating the QSIG Calling Party Number Information Element 21 9.2.3 Generating the QSIG Connected Number Information Element 21 10 Requirements for Support of Basic Services 22 10.1 Derivation of QSIG Bearer Capability Inf
14、ormation Element 22 10.2 Derivation of Media Type in SDP 22 11 Security Considerations 23 11.1 General 23 11.2 Calls from QSIG to Invalid or Restricted Numbers 23 11.3 Abuse of SIP Response Code 23 11.4 Use of the To Header URI 11.5 Use of the From Header URI 23 11.6 Abuse of Early Media 24 11.7 Pro
15、tection from Denial-of-Service Attacks 24 Annex A (normative) Implementation Conformance Statement (ICS) proforma 25Annex B (informative) Example Message Sequences 33 - ii - 1 Scope This Standard specifies signalling interworking between QSIG and the Session Initiation Protocol (SIP) in support of b
16、asic services within a corporate telecommunication network (CN) (also known as enterprise network). QSIG is a signalling protocol that operates between Private Integrated Services eXchanges (PINX) within a Private Integrated Services Network (PISN). A PISN provides circuit-switched basic services an
17、d supplementary services to its users. QSIG is specified in Ecma Standards; in particular, 2 (call control in support of basic services), 3 (generic functional protocol for the support of supplementary services), and a number of standards specifying individual supplementary services. NOTE The name Q
18、SIG was derived from the fact that it is used for signalling at the Q reference point. The Q reference point is a point of demarcation between two PINXs. SIP is an application-layer protocol for establishing, terminating, and modifying multimedia sessions. It is typically carried over IP 15, 16. Tel
19、ephone calls are considered a type of multimedia session where just audio is exchanged. SIP is defined in 10. As the support of telephony within corporate networks evolves from circuit-switched technology to Internet technology, the two technologies will coexist in many networks for a period, perhap
20、s several years. Therefore, there is a need to be able to establish, modify, and terminate sessions involving a participant in the SIP network and a participant in the QSIG network. Such calls are supported by gateways that perform interworking between SIP and QSIG. This Standard specifies SIP-QSIG
21、signalling interworking for basic services that provide a bi-directional transfer capability for speech, DTMF, facsimile, and modem media between a PISN employing QSIG and a corporate IP network employing SIP. Other aspects of interworking, e.g., the use of RTP and SDP, will differ according to the
22、type of media concerned and are outside the scope of this Standard. Call-related and call-independent signalling in support of supplementary services is outside the scope of this Standard, but support for certain supplementary services (e.g., call transfer, call diversion) could be the subject of fu
23、ture work. Interworking between QSIG and SIP permits a call originating at a user of a PISN to terminate at a user of a corporate IP network, or a call originating at a user of a corporate IP network to terminate at a user of a PISN. Interworking between a PISN employing QSIG and a public IP network
24、 employing SIP is outside the scope of this Standard. However, the functionality specified in this Standard is in principle applicable to such a scenario when deployed in conjunction with other relevant functionality (e.g., number translation, security functions, etc.). This Standard is applicable t
25、o any interworking unit that can act as a gateway between a PISN employing QSIG and a corporate IP network employing SIP. 2 Conformance In order to conform to this Standard, a gateway shall satisfy the requirements identified in the Implementation Conformance Statement (ICS) proforma in annex A. 3 R
26、eferences 1 International Standard ISO/IEC 11571 “Private Integrated Services Networks (PISN) - Addressing“ (also published by Ecma as Standard ECMA-155). 2 International Standard ISO/IEC 11572 “Private Integrated Services Network - Circuit-mode Bearer Services - Inter-Exchange Signalling Procedures
27、 and Protocol“ (also published by Ecma as Standard ECMA-143). - 1 - 3 International Standard ISO/IEC 11582 “Private Integrated Services Network - Generic Functional Protocol for the Support of Supplementary Services - Inter-Exchange Signalling Procedures and Protocol“ (also published by Ecma as Stan
28、dard ECMA-165). 4 Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels“, BCP 14, RFC 2119, March 1997. 5 Postel, J., “Transmission Control Protocol“, STD 7, RFC 793, September 1981. 6 Postel, J., “User Datagram Protocol“, STD 6, RFC 768, August 1980. 7 Dierks, T. and C. Allen, “The
29、 TLS Protocol Version 1.0“, RFC 2246, January 1999. 8 Handley, M. and V. Jacobson, “SDP: Session Description Protocol“, RFC 2327, April 1998. 9 Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer, H., Taylor, T., Rytina, I., Kalla, M., Zhang, L., and V. Paxson, “Stream Control Transmission
30、Protocol“, RFC 2960, October 2000. 10 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. 11 Rosenberg, J. and H. Schulzrinne, “Reliability of Provisional Responses in Session In
31、itiation Protocol (SIP)“, RFC 3262, June 2002. 12 Rosenberg, J. and H. Schulzrinne, “An Offer/Answer Model with Session Description Protocol (SDP)“, RFC 3264, June 2002. 13 Peterson, J., “A Privacy Mechanism for the Session Initiation Protocol (SIP)“, RFC 3323, November 2002. 14 Jennings, C., Peters
32、on, J., and M. Watson, “Private Extensions to the Session Initiation Protocol (SIP) for Asserted Identity within Trusted Networks“, RFC 3325, November 2002. 15 Postel, J., “Internet Protocol“, STD 5, RFC 791, September 1981. 16 Deering, S. and R. Hinden, “Internet Protocol, Version 6 (IPv6) Specific
33、ation“, RFC 2460, December 1998. 17 ITU-T Recommendation E.164, “The International Public Telecommunication Numbering Plan“, (1997-05). 18 Camarillo, G., Roach, A., Peterson, J., and L. Ong, “Mapping of Integrated Services Digital Network (ISDN) User Part (ISUP) Overlap Signalling to the Session Ini
34、tiation Protocol (SIP)“, RFC 3578, August 2003. 19 Rosenberg, J., “The Session Initiation Protocol (SIP) UPDATE Method“, RFC 3311, October 2002. 20 Sparks, R., “Internet Media Type message/sipfrag“, RFC 3420, November 2002. 4 Terminology and Definitions In this Standard, the key words “MUST“, “MUST
35、NOT“, “REQUIRED“, “SHALL“, “SHALL NOT“, “SHOULD“, “SHOULD NOT“, “RECOMMENDED“, “MAY“, and “OPTIONAL“ are to be interpreted as described in RFC 2119 4 and indicate requirement levels for compliant SIP implementations. For the purposes of this Standard, the following definitions apply. 4.1 External De
36、finitions The definitions in 2 and 10 apply as appropriate. 4.2 Other definitions 4.2.1 Corporate Telecommunication Network (CN) Sets of privately-owned or carrier-provided equipment that are located at geographically dispersed locations and are interconnected to provide telecommunication services t
37、o a defined group of users. - 2 - NOTE A CN can comprise a PISN, a private IP network (intranet), or a combination of the two. 4.2.2 Gateway An entity that performs interworking between a PISN using QSIG and an IP network using SIP. 4.2.3 IP Network A network (unless otherwise stated, a corporate ne
38、twork) offering connectionless packet-mode services based on the Internet Protocol (IP) as the network-layer protocol. 4.2.4 Media Stream Audio or other user information transmitted in UDP packets, typically containing RTP, in a single direction between the gateway and a peer entity participating in
39、 a session established using SIP. NOTE Normally a SIP session establishes a pair of media streams, one in each direction. 4.2.5 Private Integrated Services Network (PISN) A CN or part of a CN that employs circuit-switched technology. 4.2.6 Private Integrated Services Network Exchange (PINX) A PISN n
40、odal entity comprising switching and call handling functions and supporting QSIG signalling in accordance with 2. 5 Acronyms DNS Domain Name Service IP Internet Protocol PINX Private Integrated services Network eXchange PISN Private Integrated Services Network RTP Real-time Transport Protocol SCTP S
41、tream Control Transmission Protocol SDP Session Description Protocol SIP Session Initiation Protocol TCP Transmission Control Protocol TLS Transport Layer Security TU Transaction User UA User Agent UAC User Agent Client UAS User Agent Server UDP User Datagram Protocol 6 Background and Architecture D
42、uring the 1980s, corporate voice telecommunications adopted technology similar in principle to Integrated Services Digital Networks (ISDN). Digital circuit switches, commonly known as Private Branch eXchanges (PBX) or more formally as Private Integrated services Network eXchanges (PINX) have been in
43、terconnected by digital transmission systems to form Private Integrated Services Networks (PISN). These digital transmission systems carry voice or other payload in fixed-rate channels, typically 64 Kbit/s, and signalling in a separate channel. A technique known as common channel signalling is emplo
44、yed, whereby a single signalling channel potentially controls a number of - 3 - payload channels or bearer channels. A typical arrangement is a point-to-point transmission facility at T1 or E1 rate providing a 64 Kbit/s signalling channel and 23 or 30 bearer channels, respectively. Other arrangement
45、s are possible and have been deployed, including the use of multiple transmission facilities for a signalling channel and its logically associated bearer channels. Also, arrangements involving bearer channels at sub-64 Kbit/s have been deployed, where voice payload requires the use of codecs that pe
46、rform compression. QSIG is the internationally-standardized message-based signalling protocol for use in networks as described above. It runs in a signalling channel between two PINXs and controls calls on a number of logically associated bearer channels between the same two PINXs. The signalling ch
47、annel and its logically associated bearer channels are collectively known as an inter-PINX link. QSIG is independent of the type of transmission capabilities over which the signalling channel and bearer channels are provided. QSIG is also independent of the transport protocol used to transport QSIG
48、messages reliably over the signalling channel. QSIG provides a means for establishing and clearing calls that originate and terminate on different PINXs. A call can be routed over a single inter-PINX link connecting the originating and terminating PINX, or over several inter-PINX links in series wit
49、h switching at intermediate PINXs known as transit PINXs. A call can originate or terminate in another network, in which case it enters or leaves the PISN environment through a gateway PINX. Parties are identified by numbers, in accordance with either 17 or a private numbering plan. This basic call capability is specified in 2. In addition to basic call capability, QSIG specifies a number of further capabilities supporting the use of supplementary services in PISNs. More recently, corporate telecommunications networks
