RFC 5341

RFC 5341: The Internet Assigned Number Authority (IANA) tel URI Parameter Registry 📞✨

Part 1 of 2 🎀

Okay bestie, the title block tea 🫖: this is RFC 5341, from the Network Working Group, dated September 2008. It's a Standards Track doc, so it's a real protocol spec and not just vibes. It Updates RFC 3966 (the tel URI spec) and doesn't obsolete anything. The authors are Cullen Jennings (Cisco Systems) and Vijay K. Gurbani (Bell Laboratories, Alcatel-Lucent) 💅.

Status of This Memo 📢

This doc is an Internet standards track protocol for the whole Internet community, and it's literally asking for discussion and suggestions for improvements 💬. If you want the current standardization state and status of this protocol, check the "Internet Official Protocol Standards" (STD 1) 🔍. Distribution of this memo is unlimited 🌍.

Abstract 📇

This doc creates a brand-new Internet Assigned Number Authority (IANA) registry for tel Uniform Resource Identifier (URI) parameters and their values 🎉. It fills that registry with the parameters from the tel URI spec, plus the ones from tel URI extensions for number portability and trunk groups 🧚.

Table of Contents 🗂️

1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3.  Use of the Registry . . . . . . . . . . . . . . . . . . . . . . 2
4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 3
  4.1.  tel URI Parameters Registry . . . . . . . . . . . . . . . . 3
  4.2.  Registration Policy for tel URI Parameters  . . . . . . . . 4
5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5
7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 5
  7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 5
  7.2.  Informative References  . . . . . . . . . . . . . . . . . . 5

1. Introduction 🌸

So the tel URI (RFC 3966 [1]) is how you write down a resource that's identified by a telephone number 📱. Like a lot of URIs, it's extensible: you can define new URI parameters and new values for existing ones 🔧. Here's the tea though: RFC 3966 never set up an IANA registry for listing and standardizing those parameters and values 😬. This spec fixes that by creating the registry 🎀.

2. Terminology 💜

Okay, so when you see the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this doc, they mean exactly what [2] says they mean 🧐.

3. Use of the Registry 📚

Listen, the tel URI parameters and their values "MUST" be documented in an RFC or another permanent, readily available public spec before IANA will register them 📜. That documentation has to fully explain the syntax, intended usage, and semantics of the parameter 🔍. The whole point is to make sure independent implementations can interoperate, and to stop accidental namespace collisions between implementations of totally different features 🫶.

Documents that define tel URI parameters or parameter values MUST register them with IANA, as described in Section 4. The IANA registration policy for these is "Specification Required, Designated Expert," and we'll get into that more in Section 4.2 💅.

Some tel URI parameters only accept a set of predefined values, while others can take any value 🌈. There are also parameters with no value at all, which are just flags 🚩.

Parameters with predefined values usually have tons of values. Registering each one, or making a sub-registry for each parameter, is not appropriate 🙅. Instead, values are registered by reference: the registry entry for a parameter points to the RFCs that define its new values 🔗.

So the tel URI parameter registry has a column that says whether each parameter accepts a value. That column may contain "No value" or "Constrained" 📊. "Constrained" means certain predefined values exist, so you should consult the accompanying RFC or other permanent and readily available public specification to find the accepted set 🕵️. "No Value" means the parameter is used as a flag or doesn't have a set of predefined values, and the accompanying spec should give more info on its semantics ✨.

4. IANA Considerations 🧾

This spec creates a new IANA registry called "tel URI Parameters" 🎉.

4.1. tel URI Parameters Registry 📋

New tel URI parameters and new values for existing tel URI parameters MUST be registered with IANA 💌.

When registering a new tel URI parameter, the following information MUST be provided:

• Name of the parameter.
• Whether the parameter only accepts a set of predefined values.
• Reference to the RFC or other permanent and readily available public specification defining the parameter and new values.

When registering a new value for an existing tel URI parameter, the following information MUST be provided:

• Name of the parameter.
• Reference to the RFC or other permanent and readily available public specification providing the new value.

Here's Table 1, the starting values for this registry 💖:

Parameter Name     Predefined Values     Reference
--------------     -----------------     ---------
isub               Constrained           [RFC3966]
isub-encoding      Constrained           [RFC4715]
ext                Constrained           [RFC3966]
phone-context      Constrained           [RFC3966]
enumdi             No value              [RFC4759]
npdi               No value              [RFC4694]
rn                 Constrained           [RFC4694]
rn-context         Constrained           [RFC4694]
cic                Constrained           [RFC4694]
cic-context        Constrained           [RFC4694]
tgrp               Constrained           [RFC4904]
trunk-context      Constrained           [RFC4904]

Table 1: IANA tel URI parameter registry

4.2. Registration Policy for tel URI Parameters 🔐

Following the terminology in [3] and the actions that go with that role, the registration policy for tel URI parameters shall be "Specification Required, Designated Expert" (the former implicitly implies the latter) 🧠.

The Designated Expert can use the criteria below when deciding whether to include a new parameter in the tel URI registry. They may use them to reach a decision. (This isn't an exhaustive list. It's just representative of the issues to think about when making a fair call ⚖️.)

• If the tel URI, with the parameter under consideration, will be converted to a URI used by other signaling protocols such as the Session Initiation Protocol (SIP [5]) or H.323 [7], then the expert must consider whether this parameter merely encapsulates signaling information that is not meaningful to the processing of requests in the domain of the converted URI. For example, certain Integrated Services Digital Network (ISDN) User Part (ISUP, [8]) parameters have no equivalent corollary in SIP. So their presence or absence in a SIP URI won't hinder the normal rules for processing that URI 🙌. Other parameters may affect the normal processing rules associated with the URI. In those cases, the expert must carefully consider the ramifications, if any, of the presence of such parameters 👀.
• Certain parameters of a tel URI can be optional. These parameters act as metadata about the identifier in the tel URI 🏷️. Optional parameters should provide additional information to a service they apply to, instead of acting as enablers of that service in the first place. The service must continue to be invoked and operate normally even in the absence of these parameters 💅.

Intellectual Property 💅✨

Okay so, the IETF is being very careful here, bestie. 🫶 It takes no position on whether any Intellectual Property Rights (IPR) or other rights claimed to cover the technology in this document are valid or in scope. It also doesn't say whether any license under those rights might or might not be available. And it hasn't made any independent effort to find out whether such rights exist. 🙈 If you want the procedures for rights in RFC documents, check out BCP 78 and BCP 79. 📚

Now, if you're an implementer or user and want to see IPR disclosures that were sent to the IETF Secretariat, you can find them, along with any licensing assurances, in the IETF online IPR repository at http://www.ietf.org/ipr. 🧚 The same goes for the results of any attempt to get a general license or permission to use those proprietary rights. 💜

The IETF also invites anyone who's interested to speak up 📣 about any copyrights, patents, patent applications, or other proprietary rights that might cover technology needed to implement this standard. 🌸 Send that info to the IETF at ietf-ipr@ietf.org. 🦋 Main character energy, honestly. 👑