The IESG has received a request from the Secure Telephone Identity Revisited WG (stir) to consider changes to the following document: - 'Secure Telephone Identity Credentials: Certificates' <draft-ietf-stir-certificates-15.txt> as Proposed Standard An earlier version of this document has already been approved for publication by the IESG. Subsequent to such approval, the STIR working group identified a small number of critically important omissions in the document, which this version addresses. This IETF last call is intended to solicit comments solely on the changes between the approved version and the current version. These changes can be found at: https://www.ietf.org/rfcdiff?url1=https://www.rfc-editor.org/authors/rfc8226.txt&url2=draft-ietf-stir-certificates-15 The IESG plans to make a decision in the next few weeks, and solicits final comments on this action. Please send substantive comments to the ietf@ietf.org mailing lists by 2017-11-30. Exceptionally, comments may be sent to iesg@ietf.org instead. In either case, please retain the beginning of the Subject line to allow automated sorting. Abstract In order to prevent the impersonation of telephone numbers on the Internet, some kind of credential system needs to exist that cryptographically asserts authority over telephone numbers. This document describes the use of certificates in establishing authority over telephone numbers, as a component of a broader architecture for managing telephone numbers as identities in protocols like SIP. The file can be obtained via https://datatracker.ietf.org/doc/draft-ietf-stir-certificates/ The changes that are under review can be obtained via: https://www.ietf.org/rfcdiff?url1=https://www.rfc-editor.org/authors/rfc8226.txt&url2=draft-ietf-stir-certificates-15 IESG discussion can be tracked via https://datatracker.ietf.org/doc/draft-ietf-stir-certificates/ballot/ No IPR declarations have been submitted directly on this I-D. The document contains these normative downward references. See RFC 3967 for additional information: rfc7093: Additional Methods for Generating Key Identifiers Values (Informational - Independent Submission Editor stream) rfc3447: Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1 (Informational - IETF stream) rfc5912: New ASN.1 Modules for the Public Key Infrastructure Using X.509 (PKIX) (Informational - IETF stream) Note that rfc8017 and rfc5912 are already listed in the acceptable Downref Registry.