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Real-Time Applications and Infrastructure This document defines two application service tags for use according to RFC 3958 and RFC 4848 in the automated SIP User Agent configuration procedures defined by the SIP Forum.

The SIP Forum User Agent Configuration Recommendation defines a procedure for SIP User Agents to determine the SIP domain from which to request configuration, construct a URL for and request configuration from the configuration service provide by that domain, request that the configuration service send notices of any changes to that configuration. Two of the steps (1 and 2) in this process are accomplished in whole or in part using the DDDS Applications defined in and . This document registers the application service tags for use with these applications.

One of the mechanisms by which a SIP User Agent can determine the DNS name for the SIP domain for which it is to be configured is to accept as user input a string of decimal digits to identify the SIP domain. This digit string is called a "Provider Alias Number" (PAN). The PAN is resolved to a DNS domain name using the S-NAPTR (Simple NAPTR) DDDS application defined in . This document registers the following S-NAPTR application service tag for this purpose: Application Service TagSFUA.PAN Defining Publication

Having obtained the DNS name of a SIP domain from which to request configuration, the SIP User Agent must construct an https base URL with which to request configuration from the the configuration service for that domain. To obtain the base URL, the User Agent resolves the SIP domain name using the U-NAPTR (URI-Enabled NAPTR) DDDS application defined in . This document registers the following U-NAPTR application service tag for this purpose: Application Service TagSFUA.CFG Defining Publication

The security considerations of the various parts of the SIP Forum User Agent Configuration Recommendation are discussed in its defining specification: . There are no known security implications of registering these specific application service tag values.

This document requests registration of the Application Service Tag values "SFUA.PAN" and "SFUA.CFG" in the registry defined by .

Avaya, Inc. Status: this document has successfully completed SIP Forum Technical Working Group Last Call. The only substantive changes anticipated between the current draft and the final 1.0 version of the Recommendation are the references to this document and two other Internet Drafts on which it depends, and any revisions needed to harmonize it with the final versions of those dependencies. This memo defines a generalized mechanism for application service naming that allows service location without relying on rigid domain naming conventions (so-called name hacks). The proposal defines a Dynamic Delegation Discovery System (DDDS) Application to map domain name, application service name, and application protocol dynamically to target server and port. [STANDARDS TRACK] The purpose of this document is to define a new, straightforward Dynamic Delegation Discovery Service (DDDS) application to allow mapping of domain names to URIs for particular application services and protocols. Although defined as a new DDDS application, dubbed U-NAPTR, this is effectively an extension of the Straightforward NAPTR (S-NAPTR) DDDS Application. [STANDARDS TRACK] This 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]