The 'sip-trunking-capability' Link Relation TypeUnaffiliatedkaustubh.ietf@gmail.comCiscosreenara@cisco.comCiscoAnn ArborMIUnited States of America+1 919 392 7966deengi@cisco.comCisco7200-12 Kit Creek Rd.Research Triangle ParkNC27709United States of America+1 919 392 3266gsalguei@cisco.com
art
asapSIPSession Initiation Protocolautomatic peeringWebFingercapability set
This Informational document defines the 'sip-trunking-capability' link relation type that may be used by an enterprise telephony Session Initiation Protocol (SIP) network to retrieve a SIP trunking capability set document, which contains the capabilities and configuration requirements of an Internet Telephony Service Provider (ITSP). These technical requirements allow for seamless peering between SIP-based enterprise telephony networks and the ITSP.Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
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approved by the IESG are candidates for any level of Internet
Standard; see Section 2 of RFC 7841.
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Table of Contents
. Introduction
. The 'sip-trunking-capability' Link Relation Type
. Example Usage
. IANA Considerations
. Security Considerations
. References
. Normative References
. Informative References
Acknowledgements
Authors' Addresses
Introduction
RFC 8288 defines a way to indicate relationships between
resources on the Web. This document specifies the 'sip-trunking-capability' link
relation type according to the rules of RFC 8288. Links with this relationship type can be used to exchange capability information between potential peer devices. In the event that systems require additional parameters and configuration to negotiate communication, a well-known URI can be utilized to deliver information to potential peers, including machine-readable instructions and parameters needed for peering.
The 'sip-trunking-capability' link relation type may be used on web resources hosted by ITSPs to provide a structured and detailed capability set document. The capability set document encapsulates a set of characteristics of an ITSP, which when retrieved by enterprise telephony network devices allows for automated establishment of SIP trunking between the two telephony networks.
The 'sip-trunking-capability' Link Relation Type
A capability set document is hosted via web resources by the ITSP. A unique location of the document can be preconfigured and provided to each peer by the ITSP, or a centrally published resource can be used that dynamically generates the capability set document based on one or more Uniform Resource Identifiers (URIs) determined by the peering device. The capability set document describes the configuration parameters required to successfully establish SIP trunking between an enterprise and an ITSP network. The capability set document is composed of structured and machine-readable parameters that can be converted into configuration data to meet the communication requirements of the ITSP. The need for an enterprise telephony network to obtain a capability set document from an ITSP is documented in "Automatic Peering for SIP Trunks" .
Example Usage
This section provides an example of possible use of the 'sip-trunking-capability' relation type. The enterprise network device solicits the location of the capability set document from the well-known URI hosted by the ITSP using the WebFinger protocol . The following examples include line breaks and indentation for clarity.
GET /.well-known/webfinger?
resource=acct%3Atrunkent1456%40example.com&
rel=sip-trunking-capability
HTTP/1.1
Host: ssp1.example.com
The location of the capability set document is returned to the network device in the "href" attribute.
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Content-Type: application/jrd+json
{
"subject" : "acct:trunkent1456@example.com",
"links" :
[
{
"rel" : "sip-trunking-capability",
"href" : "https://capserver.ssp1.example.com/capdoc.json"
}
]
}
The ITSP may use an authentication framework such as OAuth 2.0 to determine the identity of the enterprise telephony network to provide the appropriate capability set document.
IANA ConsiderationsIANA has registered the 'sip-trunking-capability' link relation under the "Link Relation Types" registry as follows:
Relation Name:
sip-trunking-capability
Description:
Refers to a capability set document that defines parameters or configuration requirements for automated peering and communication-channel negotiation of the Session Initiation Protocol (SIP).
Reference:
RFC 9409
Security Considerations
The 'sip-trunking-capability' relation type is not known to introduce any new security issues not already discussed in RFC 8288 for generic use of web-linking mechanisms. However, it is recommended to exercise caution when publishing potentially sensitive capability information over unencrypted or unauthenticated channels. Additional security recommendations are outlined in the capability set document definition. See the section in "Automatic Peering for SIP Trunks" .
ReferencesNormative ReferencesWeb LinkingThis specification defines a model for the relationships between resources on the Web ("links") and the type of those relationships ("link relation types").It also defines the serialisation of such links in HTTP headers with the Link header field.Informative ReferencesSIP: Session Initiation ProtocolThis document describes Session Initiation Protocol (SIP), an application-layer control (signaling) protocol for creating, modifying, and terminating sessions with one or more participants. These sessions include Internet telephone calls, multimedia distribution, and multimedia conferences. [STANDARDS-TRACK]Uniform Resource Identifier (URI): Generic SyntaxA Uniform Resource Identifier (URI) is a compact sequence of characters that identifies an abstract or physical resource. This specification defines the generic URI syntax and a process for resolving URI references that might be in relative form, along with guidelines and security considerations for the use of URIs on the Internet. The URI syntax defines a grammar that is a superset of all valid URIs, allowing an implementation to parse the common components of a URI reference without knowing the scheme-specific requirements of every possible identifier. This specification does not define a generative grammar for URIs; that task is performed by the individual specifications of each URI scheme. [STANDARDS-TRACK]The OAuth 2.0 Authorization FrameworkThe OAuth 2.0 authorization framework enables a third-party application to obtain limited access to an HTTP service, either on behalf of a resource owner by orchestrating an approval interaction between the resource owner and the HTTP service, or by allowing the third-party application to obtain access on its own behalf. This specification replaces and obsoletes the OAuth 1.0 protocol described in RFC 5849. [STANDARDS-TRACK]WebFingerThis specification defines the WebFinger protocol, which can be used to discover information about people or other entities on the Internet using standard HTTP methods. WebFinger discovers information for a URI that might not be usable as a locator otherwise, such as account or email URIs.Automatic Peering for SIP TrunksUnaffiliatedCisco SystemsCisco SystemsThis document specifies a framework that enables enterprise telephony Session Initiation Protocol (SIP) networks to solicit and obtain a capability set document from a SIP service provider. The capability set document encodes a set of characteristics that enable easy peering between enterprise and service provider SIP networks.Work in ProgressAcknowledgements
This document resulted from the discussions in the ASAP Working Group, especially the detailed and thoughtful comments of , , , , , , , , and . Additional thanks to , , , , , , , and for their reviews and feedback.
Authors' AddressesUnaffiliatedkaustubh.ietf@gmail.comCiscosreenara@cisco.comCiscoAnn ArborMIUnited States of America+1 919 392 7966deengi@cisco.comCisco7200-12 Kit Creek Rd.Research Triangle ParkNC27709United States of America+1 919 392 3266gsalguei@cisco.com