1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-1000028.2008(R2013) IP Device (SIP UA) to Network Interface Standard As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the industrys most-pressing business priorities. T
2、hrough ATIS committees and forums, nearly 200 companies address cloud services, device solutions, emergency services, M2M communications, cyber security, ehealth, network evolution, quality of service, billing support, operations, and more. These priorities follow a fast-track development lifecycle
3、from design and innovation through solutions that include standards, specifications, requirements, business use cases, software toolkits, and interoperability testing. ATIS is accredited by the American National Standards Institute (ANSI). ATIS is the North American Organizational Partner for the 3r
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5、ERICAN NATIONAL STANDARD Approval of an American National Standard requires review by ANSI that the requirements for due process, consensus, and other criteria for approval have been met by the standards developer. Consensus is established when, in the judgment of the ANSI Board of Standards Review,
6、 substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made towards their resolu
7、tion. The use of American National Standards is completely voluntary; their existence does not in any respect preclude anyone, whether he has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards. The Ame
8、rican National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the American National
9、Standards Institute. Requests for interpretations should be addressed to the secretariat or sponsor whose name appears on the title page of this standard. CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Instit
10、ute require that action be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute. Notice of Disclaimer Adaptive Multi-Rate (AMR); Sp
11、eech processing functions; General description (GSM 06.71 version 7.0.2 Release 1998) 2.2.4 Other5TIA-127 TIA-127-A, Enhanced Variable Rate Codec (EVRC) Speech Option 3 for Wideband Spread Spectrum Digital Systems (May 2004) TIA-1016 TIA-1016-A, Source-Controlled Variable-Rate Multimode Wideband Spe
12、ech Codec (VMR-WB), Service Options 62 and 63 for Spread Spectrum Systems (January 2006) 3 DEFINITIONS 3.1 Definitions In this document, the label “must” indicates that it must be conformant to all mandatory provisions of the corresponding specification. However, it should be noted that being “confo
13、rmant to all mandatory provisions” means that it is mandatory to be able to respond to all required messages/headers, but it may not be mandatory in all circumstances to be able to send certain messages/headers. In addition, the label “must” means that the functionality must be implemented, although
14、 it is recognized that carriers, enterprise networks and devices may choose to not activate the functionality in some or all circumstances. The label “must1” indicates that all mandatory provisions of the corresponding specification must be implemented, but configuration or negotiation determines wh
15、ether the feature is used. The label “shall” indicates a mandatory requirement of this American National Standard. The label “should” indicates that it should be conformant to the corresponding specification. The label “should2” is used in the case of draft specifications for which the requirement i
16、s likely to become a “must” in a future version of this profile, after the draft specification has been promoted to an RFC. However, because draft specifications are subject to change, it is not feasible to make such specifications a “must” for the purposes of this version of the profile. Similarly,
17、 the label “should 1,2” indicates the requirement may become a “must1” in a future version of this profile. The word may denotes a optional capability that could augment the standard. The standard is fully functional without the incorporation of this optional capability. The words “see text” indicat
18、es that a description of the conformance criteria follows in this text. “N/A” indicates the corresponding specification is not required. The following definitions are applicable to the SIP UNI framework as defined in this document: Device: A device is the instrument through which an end user is conn
19、ecting to the Carrier network and contains a User Agent and a user interface. A device is a specific instance of the more generic EUF. 4This document is available from the European Telecommunications Standards Institute (ETSI). 5This document is available from the Telecommunications Industry Associa
20、tion (TIA). ATIS-1000028.2008 8 User Agent: A User Agent (UA) is a SIP construct that represents the device in a SIP-based network. It has an IP network connection on one side and a user interface connection on the other side. User interface: the user interface is the means by which a user of the DE
21、VICE interacts with the User Agent in order to initiate and receive voice communication, and is presented through something like a telephone or PC. Carrier network: A Carrier network is a SIP-based VoIP network that contains one or more elements, at least one of which is an application server (AS),
22、which is responsible for applying service logic to call requests or media streams. Application Server: An Application Server (AS) is an entity in the Carrier network that is responsible for applying service logic to call requests or media streams. Application servers implement services, in combinati
23、on with service logic in the User Agent. EUF: The end-user functions (EUF) includes end-user equipment, both the legacy terminals and NGN terminals, and also includes customer networks. End-user equipment may be either mobile or fixed. The end-user interfaces via which the EUF is connected to NGN ar
24、e supported by both physical and functional (control) interfaces. A SIP EUF contains a User Agent. SCF: The service control functions (SCF) establish, monitor, support, and release multimedia sessions and manage the users service interactions. (SIP) Proxy, Proxy Server: A Proxy or Proxy Server is an
25、 intermediary entity that acts as both a server and a client for the purpose of making requests on behalf of other clients. A proxy server primarily plays the role of routing, which means its job is to ensure that a request is sent to another entity “closer“ to the targeted user. Proxies are also us
26、eful for enforcing policy (for example, making sure a user is allowed to make a call). A proxy interprets, and, if necessary, rewrites specific parts of a request message before forwarding it. (SIP) B2B UA: A back-to-back user agent (B2BUA) is a concatenation of a SIP user agent client (UAC) and use
27、r agent server (UAS). Note: The IETF defines the B2BUA in RFC 3261 as “a logical entity that receives a request and processes it as a user agent server (UAS). In order to determine how the request should be answered, it acts as a user agent client (UAC) and generates requests. Unlike a proxy server,
28、 it maintains dialog state and shall participate in all requests sent on the dialogs it has established. Since it is a concatenation of a UAC and UAS, no explicit definitions are needed for its behavior.” (UAC and UAS behaviours are defined in RFC 3261.) A B2BUA reformulates a message before sending
29、 it as a new request. SIP PBX: A Private Branch eXchange is a telephone exchange that serves a particular business or office, as opposed to one a common carrier or telephone company operates for many businesses or for the general public. A SIP PBX has a SIP interface to the Carrier network. The SIP
30、PBX may implement a SIP Proxy or a B2BUA. The SIP PBX, in the context of this specification, appears to the network as if it is a device or EUF, even though the User Agent may be in the PBX, or in the physical device connected to the PBX. User Network Interface: The User-Network Interface (UNI) is t
31、he interface between the User Agent (UA) and the network. Services: The collection of behaviors to be applied to communications requests on behalf of the end user. 4 ABBREVIATIONS 4.1 Abbreviations ABNF Augmented BNF ATIS-1000028.2008 9 AMR Adaptive Multirate (codec) AMR NB AMR Narrowband AMR WB AMR
32、 Wideband ANSI American National Standards Institute B2BUA Back-to-Back User Agent BNF Backus-Naur Form CPE Customer Premises Equipment CSC-FE Call Session Control Functional Entity DNS Domain Name Service DTMF Dual Tone Multi Frequency EUF End-User Functions EVRC Enhanced Variable Rate Codec FQDN F
33、ully Qualified Domain Name HTTP Hypertext Transport Protocol IBC-FE Interconnection Border gateway Control Functional Entity IETF Internet Engineering Task Force IP Internet Protocol ISDN Integrated Services Digital Network ISO/IEC International Standardization Organization/International Electrotech
34、nical Commission ITU-T International Telecommunications Union Telecommunication IVR Interactive Voice Response KPML Key Press Markup Language MIME Multipurpose Internet Mail Extensions MPEG Moving Picture Experts Group MWI Message Waiting Indication NAT Network Address TranslationNGN Next Generation
35、 Network NGN-TE NGN Terminal Equipment PBX Private Branch eXchange PCM Pulse Code Modulation PoC Push to talk over Cellular PSTN Public Switched Telephone Network QoS Quality of Service RFC Request for Comments RTCP RTP Control Protocol RTP Real-time Transport Protocol SCF Service Control Functions
36、SDP Session Description Protocol SIP Session Initiation Protocol SIPS Session Initiation Protocol Secure SMV Selectable Mode Vocoders SRTP Secure Real-time Transport Protocol TCP Transmission Control Protocol TLS Transport Layer Security UA User Agent UAC User Agent Client UAS User Agent Server UDP
37、User Datagram Protocol UI User-Interface UNI User-Network Interface URI Uniform Resource Identifier VMR-WB Variable-Rate Multi-Mode Wideband VoIP Voice over IP VPN Virtual Private Network WPA Wi-Fi Protected Access XML Extensible Markup Language 5 REFERENCE MODEL The User-Network Interface (UNI) is
38、the interface between the User Agent (UA) and the network. The network is viewed here as more or less a single entity, although in fact different signaling will interact with different network elements. ATIS-1000028.2008 10 Figure 1.a: User-Network Interface Model for SIP phone connected directly to
39、 Carrier Network The UNI for SIP phones connected to the SIP network covers both residential and enterprise applications where the customer wants to take full advantage of the future SIP multi-media capabilities. This specification applies equally to SIP “Hard Phones” and “Soft Phones”. The services
40、 are implemented in the SIP UA, in the Application Server, or in a combination of the two, depending on the specific service. Service Provider SIP PBXFigure 1.b: User-Network Interface Model for SIP PBX to Service Provider The SIP PBX to Service provider scenario is aimed at the enterprise market. T
41、he UNI allows for the SIP PBX to be managed by either the enterprise, or the Service Provider. The UNI does not restrict the types of terminals, and can include both SIP “Hard Phones” and “Soft Phones”. In the case of SIP Phones, the SIP PBX can act as either a proxy or a B2B UA. This specification
42、assumes that the PBX will register users individually, however it is recognized that there may be value in supporting the capability for a SIP PBX to bulk register users. This later case, referred to as “aggregate end points”, is for further study. ATIS-1000028.2008 11 6 ASSUMPTIONS This collection
43、of baseline protocols is designed to enable implementation of basic function phones as well as rich feature phones. This informative section is intended to provide some background for the collection of normative specifications defined in the sections that follow. The specification in this document a
44、pplies to the implementation of the components on either side of the SIP UNI. The specification does not in general apply to the use of these components, which is a local matter for the carrier. For example, this document specifies that TLS shall be supported. This means that equipment must include
45、the functionality necessary to initiate calls using TLS. However, the carrier may choose not to use it for a given call, or even to disable this capability in a given deployment. This specification is intended to maximize interoperability, not to restrict a carriers business decisions. Using TLS ove
46、r TCP is the preferred transport for SIP messages, however it is recognized that many SIP devices use UDP, so UDP is also a requirement of the Network Edge. In addition, devices shall support SRTP for media encryption, although some configurations may not use SRTP for some calls. Other encryption is
47、 also possible but not required, such as IPSec as a VPN-tunneling mechanism to the service provider. IPSec is of particular interest for several reasons including: its common use over numerous interconnections, such as WiFi which may or may not also have additional security mechanisms such as WPA; a
48、nd its use in the PacketCable Security Specification, http:/ January 2005. Symmetric RTP and outbound proxy support is part of the Baseline Profile so that signaling and media can traverse typical consumer firewalls and NATs using “network hosted NAT traversal”, with minimum impact on the device imp
49、lementation. By adjusting the SIP Registration timeout to keep a NAT pinhole open, (for example, through correction of IP addresses and port numbers in SIP messages and SDPs) symmetric UDP allows the media to flow through typical firewalls and NATs, and can be directed to the appropriate target. There are deployment topologies in which symmetric RTP is not required. The outbound proxy for a device may be set. The setting may require that all signaling packets shall be sent to the outbound proxy or that only in
