Note on Usage of Phone Number in the From Field of SIP Messaging V 1.0
draft-cooke-sip-rfc3261bis-00

Internet-Draft                                                  R. Cooke
Intended status: Informational                            June 2, 2023
Expires: December 4, 2023

        Note on Usage of Phone Number in the From Field of SIP
                           Messaging V 1.0
               <draft-cooke-sip-rfc3261bis-00.txt>

Abstract

   This document proposes adding a note to the current SIP messaging
   standards to clarify the usage of the phone number within the From
   field. The note advises against duplicating the phone number inside
   the double angle brackets (<>) when it is already included within the
   double quotation marks (" "). This recommendation aims to avoid the
   display of unknown numbers caused by devices prioritizing SIP
   signaling information over locally stored contact information.

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   Table of Contents

   1. Introduction......................................................3
   2. Terminology.......................................................3
   3. The From Header Field.............................................4
   4. Examples..........................................................4
   5. Rationale.........................................................5
   6. Compatibility and Impact..........................................5
   7. Security Considerations...........................................6
   8. References........................................................6
   9. Author's Address.................................................10

1. Introduction

   The From header field in Session Initiation Protocol (SIP) messaging
   is used to indicate the initiator of a SIP request. It typically includes
   a display name and a SIP or tel URI. The display name is enclosed within
   double quotation marks (" ") and the URI is enclosed within double angle
   brackets (<>).

2. Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP 14
   [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as
   shown here.

3. The From Header Field

   The From header field is defined in Section 8.1.1.3 of RFC 3261 [RFC3261].
   It is used to indicate the initiator of a SIP request and contains a
   display name and a SIP or tel URI.

   The display name is typically used to convey the caller's name or a
   recognizable identifier. It is enclosed within double quotation marks (" ").
   The URI includes the SIP or tel scheme followed by the user's address,
   enclosed within double angle brackets (<>) to indicate a URI.

   In some cases, the display name includes the phone number in addition to
   the caller's name. However, it is important to note that including the phone
   number within the display name can lead to confusion and display issues on
   certain devices that prioritize SIP signaling information over locally stored
   contact information. Consequently, the recipient may perceive the call as
   originating from an unknown number, even though the user's name is displayed.

4. Examples

   The following examples illustrate the usage of the From header field:

   From: "Alice" <sip:alice@example.com>;tag=12345678
   From: "Bob" <sip:bob@example.com>;tag=98765432
   From: "Charlie" <tel:+123456789>;tag=87654321

5. Rationale

   Including the phone number within the display name of the From header field
   is unnecessary and can lead to display issues on certain devices. The display
   name is primarily used to convey the caller's name or a recognizable identifier,
   while the URI contains the necessary contact information.

   By avoiding the duplication of the phone number within the display name, we
   ensure that devices prioritize the locally stored contact information and
   display the caller's name instead of an unknown number.

6. Compatibility and Impact

   This note on the usage of the From header field has no impact on the
   interoperability between SIP implementations. It is intended to provide
   clarification and best practices to improve the user experience.

7. Security Considerations

   This document does not introduce any new security considerations beyond
   those already discussed in the SIP specifications [RFC3261].

8. References

   8.1. Normative References

      [RFC2119]   Bradner, S., "Key words for use in RFCs to Indicate
                  Requirement Levels", BCP 14, RFC 2119,
                  DOI 10.17487/RFC2119, March 1997,
                  <https://www.rfc-editor.org/rfc/rfc2119>.

      [RFC3261]   Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
                  A., Peterson, J., Sparks, R., Handley, M., and E. Schooler,
                  "SIP: Session Initiation Protocol", RFC 3261,
                  DOI 10.17487/RFC3261, June 2002,
                  <https://www.rfc-editor.org/rfc/rfc3261>.

      [RFC8174]   Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
                  2119 Key Words", BCP 14, RFC 8174,
                  DOI 10.17487/RFC8174, May 2017,
                  <https://www.rfc-editor.org/rfc/rfc8174>.

9. Author's Address

   Raymond Cooke
   Example Organization
   Email: rcooke@example.com