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RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals
RFC 4733

Revision differences

Document history

Date Rev. By Action
2020-01-21
15 (System) Received changes through RFC Editor sync (added Verified Errata tag)
2018-12-20
15 (System)
Received changes through RFC Editor sync (changed abstract to 'This memo describes how to carry dual-tone multifrequency (DTMF) signalling, other tone signals, and telephony events …
Received changes through RFC Editor sync (changed abstract to 'This memo describes how to carry dual-tone multifrequency (DTMF) signalling, other tone signals, and telephony events in RTP packets. It obsoletes RFC 2833.

This memo captures and expands upon the basic framework defined in RFC 2833, but retains only the most basic event codes. It sets up an IANA registry to which other event code assignments may be added. Companion documents add event codes to this registry relating to modem, fax, text telephony, and channel-associated signalling events. The remainder of the event codes defined in RFC 2833 are conditionally reserved in case other documents revive their use.

This document provides a number of clarifications to the original document. However, it specifically differs from RFC 2833 by removing the requirement that all compliant implementations support the DTMF events. Instead, compliant implementations taking part in out-of-band negotiations of media stream content indicate what events they support. This memo adds three new procedures to the RFC 2833 framework: subdivision of long events into segments, reporting of multiple events in a single packet, and the concept and reporting of state events. [STANDARDS-TRACK]')
2012-08-22
15 (System) post-migration administrative database adjustment to the No Objection position for Sam Hartman
2012-08-22
15 (System) post-migration administrative database adjustment to the No Objection position for Russ Housley
2007-01-02
15 (System) This was part of a ballot set with: draft-ietf-avt-rfc2833bisdata
2007-01-02
15 Amy Vezza State Changes to RFC Published from RFC Ed Queue by Amy Vezza
2007-01-02
15 Amy Vezza [Note]: 'RFC 4733' added by Amy Vezza
2006-12-18
15 (System) RFC published
2006-11-08
15 (System) Request for Early review by SECDIR is assigned to Magnus Nystrom
2006-11-08
15 (System) Request for Early review by SECDIR is assigned to Magnus Nystrom
2006-08-28
15 Amy Vezza State Changes to RFC Ed Queue from Approved-announcement sent by Amy Vezza
2006-08-25
15 Amy Vezza IESG state changed to Approved-announcement sent
2006-08-25
15 Amy Vezza IESG has approved the document
2006-08-25
15 Amy Vezza Closed "Approve" ballot
2006-08-25
15 Amy Vezza State Changes to Approved-announcement to be sent from IESG Evaluation::AD Followup by Amy Vezza
2006-07-09
15 Russ Housley [Ballot Position Update] Position for Russ Housley has been changed to No Objection from Discuss by Russ Housley
2006-07-08
15 Cullen Jennings State Changes to IESG Evaluation::AD Followup from Approved-announcement to be sent by Cullen Jennings
2006-06-16
15 Cullen Jennings State Changes to Approved-announcement to be sent from IESG Evaluation::AD Followup by Cullen Jennings
2006-06-16
15 (System) New version available: draft-ietf-avt-rfc2833bis-15.txt
2006-06-15
15 Cullen Jennings All issues resolved other than the deprecated code point reuse which is still in discussion.
2006-06-06
15 (System) Sub state has been changed to AD Follow up from New Id Needed
2006-06-06
14 (System) New version available: draft-ietf-avt-rfc2833bis-14.txt
2006-06-04
15 Brian Carpenter [Ballot Position Update] New position, No Objection, has been recorded for Brian Carpenter by Brian Carpenter
2006-05-31
15 Cullen Jennings State Changes to IESG Evaluation::Revised ID Needed from IESG Evaluation::AD Followup by Cullen Jennings
2006-05-26
15 (System) Removed from agenda for telechat - 2006-05-25
2006-05-25
15 Amy Vezza State Changes to IESG Evaluation::AD Followup from IESG Evaluation by Amy Vezza
2006-05-25
15 Mark Townsley [Ballot Position Update] New position, No Objection, has been recorded for Mark Townsley by Mark Townsley
2006-05-25
15 David Kessens [Ballot Position Update] New position, No Objection, has been recorded for David Kessens by David Kessens
2006-05-25
15 Jari Arkko
[Ballot comment]
> If the specification is created by an outside body, the IETF-appointed expert must ...

Trying to understand if the rules are clear …
[Ballot comment]
> If the specification is created by an outside body, the IETF-appointed expert must ...

Trying to understand if the rules are clear enough to be followed.
What's "an outside body"? Does it cover only other SDOs, companies,
persons? What about individual submissions through the RFC Editor?
And wouldn't the same checks need to be done even if the document
was an IETF product?

I'd suggest dropping the "if" part and just saying what the
expert needs to do.

Nits (I get these from a script that I run for all documents):

s/occurence/occurrence/
s/occuring/occurring/
two ways to write echo canceller / cancellor
s/renable/re-enable/
2006-05-25
15 Jari Arkko
[Ballot comment]
> If the specification is created by an outside body, the IETF-appointed expert must ...

Trying to understand if the rules are clear …
[Ballot comment]
> If the specification is created by an outside body, the IETF-appointed expert must ...

Trying to understand if the rules are clear enough to be followed.
What's "an outside body"? Does it cover only other SDOs, companies,
persons? What about individual submissions through the RFC Editor?
And wouldn't the same checks need to be done even if the document
was an IETF product?

I'd suggest dropping the "if" part and just saying what the
expert needs to do.
2006-05-25
15 Jari Arkko [Ballot Position Update] New position, No Objection, has been recorded for Jari Arkko by Jari Arkko
2006-05-25
15 Jon Peterson [Ballot Position Update] New position, No Objection, has been recorded for Jon Peterson by Jon Peterson
2006-05-25
15 Bill Fenner [Ballot Position Update] New position, No Objection, has been recorded for Bill Fenner by Bill Fenner
2006-05-24
15 Ross Callon [Ballot Position Update] New position, No Objection, has been recorded for Ross Callon by Ross Callon
2006-05-24
15 Ted Hardie [Ballot Position Update] New position, No Objection, has been recorded for Ted Hardie by Ted Hardie
2006-05-24
15 Sam Hartman [Ballot Position Update] Position for Sam Hartman has been changed to No Objection from Discuss by Sam Hartman
2006-05-23
15 Sam Hartman
[Ballot discuss]
I question whether the requirement that all implementations of the
telephone event codes must implement SRTP is reasonable.  Is the
vendor community actually …
[Ballot discuss]
I question whether the requirement that all implementations of the
telephone event codes must implement SRTP is reasonable.  Is the
vendor community actually behind this requirement?

I also question whether this requirement will actually give us
interoperability without a mandatory-to-implement key management solution .

If this is really going to be implemented and will add real-world
security, I'm all for it.  If it is a requirement that is added but
that will not be implemented in practice, I would rather see us
document the vulnerability and publish a spec that matches
implementation reality.  There are cases where it is appropriate for
specs to lead implementations in security requirements; I'm nott sure
this is one of them.  But again, if there is strong support for this
requirement I can be convinced to withdraw the discuss.
2006-05-23
15 Sam Hartman [Ballot Position Update] New position, Discuss, has been recorded for Sam Hartman by Sam Hartman
2006-05-23
15 Dan Romascanu [Ballot Position Update] Position for Dan Romascanu has been changed to No Objection from Undefined by Dan Romascanu
2006-05-23
15 Dan Romascanu
[Ballot comment]
1. idnits complains wrt. 2119 boilerplate on both documents. The reason seems to be that the recommended 2119 bolerplate text is not reproduced …
[Ballot comment]
1. idnits complains wrt. 2119 boilerplate on both documents. The reason seems to be that the recommended 2119 bolerplate text is not reproduced ad-literam.

2. The abbreviations list in draft-ietf-avt-rfc2833bisdata-06.txt is not complete. PBX and MIME are being used in the document and not included in the list
2006-05-23
15 Dan Romascanu [Ballot Position Update] New position, Undefined, has been recorded for Dan Romascanu by Dan Romascanu
2006-05-22
15 Russ Housley [Ballot comment]
s/IPSEC/IPsec/
2006-05-22
15 Russ Housley
[Ballot discuss]
draft-ietf-avt-rfc2833bis-13:
 
  The title page header and the Introduction need to mention that
  this document obsoletes RFC 2833.

  …
[Ballot discuss]
draft-ietf-avt-rfc2833bis-13:
 
  The title page header and the Introduction need to mention that
  this document obsoletes RFC 2833.

  The security considerations section says:
  >
  > Because the data compression used with this payload format is applied
  > end-to-end, encryption may be performed after compression so there is
  > no conflict between the two operations.
  >
  Encryption MUST be performed after compression.  Compression after
  encryption will result in very poor compression performance indeed.

  draft-ietf-avt-rfc2833bisdata-06:

  The title page header needs to indicate that this document updates
  rfc2833bis.
2006-05-22
15 Russ Housley [Ballot Position Update] New position, Discuss, has been recorded for Russ Housley by Russ Housley
2006-05-22
15 Lars Eggert [Ballot Position Update] Position for Lars Eggert has been changed to Yes from Undefined by Lars Eggert
2006-05-22
15 Lars Eggert
[Ballot comment]
INTRODUCTION, para. 15:

>    Companion documents add event codes to this registry relating to
>    modem, fax, text telephony, and channel-associated …
[Ballot comment]
INTRODUCTION, para. 15:

>    Companion documents add event codes to this registry relating to
>    modem, fax, text telephony, and channel-associated signalling events.
>    The remainder of the event codes defined in RFC 2833 are deprecated.

        What are the companion documents? I'm guessing at least
        draft-ietf-avt-rfc2833bisdata-06, which isn't cited. Are there others?
        Without this information, it's hard to know what the "remainder of the
        event codes defined in RFC 2833" that are being deprecated actually are.
2006-05-22
15 Lars Eggert [Ballot Position Update] New position, Undefined, has been recorded for Lars Eggert by Lars Eggert
2006-05-21
15 Lisa Dusseault [Ballot Position Update] New position, No Objection, has been recorded for Lisa Dusseault by Lisa Dusseault
2006-05-16
15 Magnus Westerlund [Ballot Position Update] New position, Recuse, has been recorded for Magnus Westerlund by Magnus Westerlund
2006-05-09
13 (System) New version available: draft-ietf-avt-rfc2833bis-13.txt
2006-05-08
15 Cullen Jennings [Ballot Position Update] New position, Yes, has been recorded for Cullen Jennings
2006-05-08
15 Cullen Jennings Ballot has been issued by Cullen Jennings
2006-05-08
15 Cullen Jennings Created "Approve" ballot
2006-05-08
15 Cullen Jennings Placed on agenda for telechat - 2006-05-25 by Cullen Jennings
2006-05-08
15 Cullen Jennings State Changes to IESG Evaluation from Waiting for AD Go-Ahead::Revised ID Needed by Cullen Jennings
2006-05-08
15 Cullen Jennings State Changes to Waiting for AD Go-Ahead::Revised ID Needed from Waiting for AD Go-Ahead by Cullen Jennings
2006-05-04
15 (System) State has been changed to Waiting for AD Go-Ahead from In Last Call by system
2006-05-02
15 Yoshiko Fong
IANA Last Call Comments:


Upon approval of this document the IANA will update the references to be this document
for the following:

MIME Media types …
IANA Last Call Comments:


Upon approval of this document the IANA will update the references to be this document
for the following:

MIME Media types
audio/telephone-event
audio/tone
http://www.iana.org/assignments/media-types/audio/

RTP Payloads
telephone-event
tone
http://www.iana.org/assignments/rtp-parameters


IANA will also create a new registry for the audio/telephone-event types with the initial
assignments from section 7 of the document. Registration procedures will be Specification
Required and Expert Review.

An expert will need to be appointed.

Should this new registry be placed at the following location?:
http://www.iana.org/assignments/media-type-sub-parameters

Do we understand the IANA Actions correctly?
2006-04-06
15 Amy Vezza Last call sent
2006-04-06
15 Amy Vezza State Changes to In Last Call from Last Call Requested by Amy Vezza
2006-04-06
15 Cullen Jennings Last Call was requested by Cullen Jennings
2006-04-06
15 (System) Ballot writeup text was added
2006-04-06
15 (System) Last call text was added
2006-04-06
15 (System) Ballot approval text was added
2006-04-06
15 Cullen Jennings State Changes to Last Call Requested from AD Evaluation by Cullen Jennings
2006-03-29
15 Cullen Jennings Changed PROTO sheperd to Colin Perkins
2006-03-29
15 Cullen Jennings [Note]: 'PROTO shepherd Colin Perkins <csp@csperkins.org>' added by Cullen Jennings
2006-03-28
15 Cullen Jennings
PROTO write up

Date:    Thu, 01 Dec 2005 15:14:20 +0100
From:    Magnus Westerlund
To:      IESG Secretary
cc:      Allison Mankin …
PROTO write up

Date:    Thu, 01 Dec 2005 15:14:20 +0100
From:    Magnus Westerlund
To:      IESG Secretary
cc:      Allison Mankin ,
Colin Perkins
Subject: Request to publish: draft-ietf-avt-rfc2833bis and draft-ietf-avt-rfc28
  33bisdata

Hi,

The AVT WG would like to request that draft-ietf-avt-rfc2833bis are
published as proposed standards which obsolete RFC 2833. AVT also
request that draft-ietf-avt-rfc2833bisdata is published as proposed
standard. I, Magnus Westerlund will be WG shepherd of these documents.
The documents belong together and should be published as consecutively
numbered RFC. They have also gone through WG last call together,
therefore only a single writeup will be provided.


    1.a) Have the chairs personally reviewed this version of the Internet
        Draft (ID), and in particular, do they believe this ID is ready
        to forward to the IESG for publication?
Yes

    1.b) Has the document had adequate review from both key WG members
        and key non-WG members?  Do you have any concerns about the
        depth or breadth of the reviews that have been performed?

Yes,

    1.c) Do you have concerns that the document needs more review from a
        particular (broader) perspective (e.g., security, operational
        complexity, someone familiar with AAA, etc.)?

No

    1.d) Do you have any specific concerns/issues with this document that
        you believe the ADs and/or IESG should be aware of?  For
        example, perhaps you are uncomfortable with certain parts of the
        document, or have concerns whether there really is a need for
        it.  In any event, if your issues have been discussed in the WG
        and the WG has indicated it that it still wishes to advance the
        document, detail those concerns in the write-up.

No

    1.e) How solid is the WG consensus behind this document? Does it
        represent the strong concurrence of a few individuals, with
        others being silent, or does the WG as a whole understand and
        agree with it?

Solid consensus


    1.f) Has anyone threatened an appeal or otherwise indicated extreme
        discontent?  If so, please summarise the areas of conflict in
        separate email to the Responsible Area Director.

No

    1.g) Have the chairs verified that the document adheres to all of the
        ID nits? (see http://www.ietf.org/ID-Checklist.html).

Yes

    1.h) Is the document split into normative and informative references?
        Are there normative references to IDs, where the IDs are not
        also ready for advancement or are otherwise in an unclear state?
        (note here that the RFC editor will not publish an RFC with
        normative references to IDs, it will delay publication until all
        such IDs are also ready for publication as RFCs.)

Yes

    1.i) For Standards Track and BCP documents, the IESG approval
        announcement includes a write-up section with the following
        sections:

Technical Summary:

draft-ietf-avt-rfc2833bis:

This document defines the RTP Payload format for telephony events over
RTP and the usage of DTMF in this payload format. It also establish a
registry in which further telephony events using this payload format may
be registered in. The document also defines an RTP Payload format for
tones used in telephony systems. The payload format is capable of
describing single, multiple or modulated tones.

draft-ietf-avt-rfc2833bisdata:

This document defines 31 additional events to be used with the RTP
payload format for telephony events defined in
draft-ietf-avt-rfc2833bis. The defined event cover the usage with a
number of ITU specifications such as V.8, V.8 bis, V.21, V.25,
V.32/V.32bis, and T.30.

Working Group Summary:

There is consensus in the WG to publish these documents.

Protocol Quality:

These documents are updates of RFC 2833 which is obsoleted. The
implementation experience for RFC 2833 has been taken into account in
these updates. The documents have been reviewed by both IETF and ITU-T
Study Group 16.
2006-03-28
15 Cullen Jennings Shepherding AD has been changed to Cullen Jennings from Allison Mankin
2006-01-14
15 Allison Mankin
Asked for a reviewer from the SIPPING or IPTEL world more than a
week ago - deadline for review Jan 19.  But no reviewer has …
Asked for a reviewer from the SIPPING or IPTEL world more than a
week ago - deadline for review Jan 19.  But no reviewer has
said they are reviewing.  Dean had said he would ask Jiri Kuthan
and Jonathan Rosenberg said he is looking at the reviewer question.
Perhaps will un-delegate the invitation to reviewers and ask
for URGENT review myself now.
2006-01-06
15 Allison Mankin [Note]: 'PROTO shepherd magnus.westerlund@ericsson.com' added by Allison Mankin
2006-01-06
15 Allison Mankin Note field has been cleared by Allison Mankin
2006-01-06
15 Allison Mankin State Changes to AD Evaluation from Publication Requested by Allison Mankin
2005-12-07
15 Dinara Suleymanova State Changes to Publication Requested from AD is watching::AD Followup by Dinara Suleymanova
2005-11-10
12 (System) New version available: draft-ietf-avt-rfc2833bis-12.txt
2005-11-09
15 (System) Sub state has been changed to AD Follow up from New Id Needed
2005-11-09
11 (System) New version available: draft-ietf-avt-rfc2833bis-11.txt
2005-11-06
15 Allison Mankin [Note]: 'One WGLC done, has not done media type review' added by Allison Mankin
2005-11-06
15 Allison Mankin Draft Added by Allison Mankin in state AD is watching
2005-09-29
10 (System) New version available: draft-ietf-avt-rfc2833bis-10.txt
2005-06-15
09 (System) New version available: draft-ietf-avt-rfc2833bis-09.txt
2005-02-16
08 (System) New version available: draft-ietf-avt-rfc2833bis-08.txt
2005-01-25
07 (System) New version available: draft-ietf-avt-rfc2833bis-07.txt
2004-11-19
06 (System) New version available: draft-ietf-avt-rfc2833bis-06.txt
2004-10-22
05 (System) New version available: draft-ietf-avt-rfc2833bis-05.txt
2004-02-12
04 (System) New version available: draft-ietf-avt-rfc2833bis-04.txt
2003-07-02
03 (System) New version available: draft-ietf-avt-rfc2833bis-03.txt
2002-12-06
02 (System) New version available: draft-ietf-avt-rfc2833bis-02.txt
2002-10-22
01 (System) New version available: draft-ietf-avt-rfc2833bis-01.txt
2002-05-29
00 (System) New version available: draft-ietf-avt-rfc2833bis-00.txt