rfc8865v4.txt   rfc8865.txt 
Internet Engineering Task Force (IETF) C. Holmberg Internet Engineering Task Force (IETF) C. Holmberg
Request for Comments: 8865 Ericsson Request for Comments: 8865 Ericsson
Updates: 8373 G. Hellström Updates: 8373 G. Hellström
Category: Standards Track Gunnar Hellström Accessible Communication Category: Standards Track Gunnar Hellström Accessible Communication
ISSN: 2070-1721 November 2020 ISSN: 2070-1721 January 2021
T.140 Real-Time Text Conversation over WebRTC Data Channels T.140 Real-Time Text Conversation over WebRTC Data Channels
Abstract Abstract
This document specifies how a Web Real-Time Communication (WebRTC) This document specifies how a Web Real-Time Communication (WebRTC)
data channel can be used as a transport mechanism for real-time text data channel can be used as a transport mechanism for real-time text
using the ITU-T Protocol for multimedia application text conversation using the ITU-T Protocol for multimedia application text conversation
(Recommendation ITU-T T.140) and how the Session Description Protocol (Recommendation ITU-T T.140) and how the Session Description Protocol
(SDP) offer/answer mechanism can be used to negotiate such a data (SDP) offer/answer mechanism can be used to negotiate such a data
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received public review and has been approved for publication by the received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841. Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata, Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8865. https://www.rfc-editor.org/info/rfc8865.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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Reference: RFC 8865 Reference: RFC 8865
9.2. SDP 'fmtp' Attribute 9.2. SDP 'fmtp' Attribute
This document defines the usage of the SDP 'fmtp' attribute, if this This document defines the usage of the SDP 'fmtp' attribute, if this
attribute is included in an SDP 'dcsa' attribute associated with a attribute is included in an SDP 'dcsa' attribute associated with a
T.140 real-time text session over a WebRTC data channel. The usage T.140 real-time text session over a WebRTC data channel. The usage
is defined in Section 4.2.1. is defined in Section 4.2.1.
The usage level "dcsa(t140)" has been added to the registration of The usage level "dcsa (t140)" has been added to the registration of
the SDP 'fmtp' attribute in the "Session Description Protocol (SDP) the SDP 'fmtp' attribute in the "Session Description Protocol (SDP)
Parameters" registry as follows: Parameters" registry as follows:
Contact name: IESG Contact name: IESG
Contact email: iesg@ietf.org Contact email: iesg@ietf.org
Attribute name: fmtp Attribute name: fmtp
Usage level: dcsa(t140) Usage level: dcsa (t140)
Purpose: Indicate format parameters for a T.140 data channel, such Purpose: Indicate format parameters for a T.140 data channel, such
as maximum character transmission rates. as maximum character transmission rates.
Reference: RFC 8865 Reference: RFC 8865
9.3. SDP Language Attributes 9.3. SDP Language Attributes
This document modifies the usage of the SDP 'hlang-send' and 'hlang- This document modifies the usage of the SDP 'hlang-send' and 'hlang-
recv' attributes, if these attributes are included in SDP 'dcsa' recv' attributes, if these attributes are included in SDP 'dcsa'
attributes associated with a T.140 data channel. The modified usage attributes associated with a T.140 data channel. The modified usage
is described in Section 4.2.2. is described in Section 4.2.2.
The usage level "dcsa(t140)" has been added to the registration of The usage level "dcsa (t140)" has been added to the registration of
the SDP 'hlang-send' attribute in the "Session Description Protocol the SDP 'hlang-send' attribute in the "Session Description Protocol
(SDP) Parameters" registry as follows: (SDP) Parameters" registry as follows:
Contact name: IESG Contact name: IESG
Contact email: iesg@ietf.org Contact email: iesg@ietf.org
Attribute name: hlang-send Attribute name: hlang-send
Usage level: dcsa(t140) Usage level: dcsa (t140)
Purpose: Negotiate the language to be used on a T.140 data channel. Purpose: Negotiate the language to be used on a T.140 data channel.
Reference: RFC 8865 Reference: RFC 8865
The usage level "dcsa(t140)" has been added to the registration of The usage level "dcsa (t140)" has been added to the registration of
the SDP 'hlang-recv' attribute in the "Session Description Protocol the SDP 'hlang-recv' attribute in the "Session Description Protocol
(SDP) Parameters" registry as follows: (SDP) Parameters" registry as follows:
Contact name: IESG Contact name: IESG
Contact email: iesg@ietf.org Contact email: iesg@ietf.org
Attribute name: hlang-recv Attribute name: hlang-recv
Usage level: dcsa(t140) Usage level: dcsa (t140)
Purpose: Negotiate the language to be used on a T.140 data channel. Purpose: Negotiate the language to be used on a T.140 data channel.
Reference: RFC 8865 Reference: RFC 8865
9.4. SDP Media Direction Attributes 9.4. SDP Media Direction Attributes
This document modifies the usage of the SDP 'sendonly', 'recvonly', This document modifies the usage of the SDP 'sendonly', 'recvonly',
'sendrecv', and 'inactive' attributes, if these attributes are 'sendrecv', and 'inactive' attributes, if these attributes are
included in SDP 'dcsa' attributes associated with a T.140 data included in SDP 'dcsa' attributes associated with a T.140 data
channel. The modified usage is described in Section 4.2.3. channel. The modified usage is described in Section 4.2.3.
The usage level "dcsa(t140)" has been added to the registration of The usage level "dcsa (t140)" has been added to the registration of
the SDP 'sendonly' attribute in the "Session Description Protocol the SDP 'sendonly' attribute in the "Session Description Protocol
(SDP) Parameters" registry as follows: (SDP) Parameters" registry as follows:
Contact name: IESG Contact name: IESG
Contact email: iesg@ietf.org Contact email: iesg@ietf.org
Attribute name: sendonly Attribute name: sendonly
Usage level: dcsa(t140) Usage level: dcsa (t140)
Purpose: Negotiate the direction in which real-time text can be sent Purpose: Negotiate the direction in which real-time text can be sent
on a T.140 data channel. on a T.140 data channel.
Reference: RFC 8865 Reference: RFC 8865
The usage level "dcsa(t140)" has been added to the registration of The usage level "dcsa (t140)" has been added to the registration of
the SDP 'recvonly' attribute in the "Session Description Protocol the SDP 'recvonly' attribute in the "Session Description Protocol
(SDP) Parameters" registry as follows: (SDP) Parameters" registry as follows:
Contact name: IESG Contact name: IESG
Contact email: iesg@ietf.org Contact email: iesg@ietf.org
Attribute name: recvonly Attribute name: recvonly
Usage level: dcsa(t140) Usage level: dcsa (t140)
Purpose: Negotiate the direction in which real-time text can be sent Purpose: Negotiate the direction in which real-time text can be sent
on a T.140 data channel. on a T.140 data channel.
Reference: RFC 8865 Reference: RFC 8865
The usage level "dcsa(t140)" has been added to the registration of The usage level "dcsa (t140)" has been added to the registration of
the SDP 'sendrecv' attribute in the "Session Description Protocol the SDP 'sendrecv' attribute in the "Session Description Protocol
(SDP) Parameters" registry as follows: (SDP) Parameters" registry as follows:
Contact name: IESG Contact name: IESG
Contact email: iesg@ietf.org Contact email: iesg@ietf.org
Attribute name: sendrecv Attribute name: sendrecv
Usage level: dcsa(t140) Usage level: dcsa (t140)
Purpose: Negotiate the direction in which real-time text can be sent Purpose: Negotiate the direction in which real-time text can be sent
on a T.140 data channel. on a T.140 data channel.
Reference: RFC 8865 Reference: RFC 8865
The usage level "dcsa(t140)" has been added to the registration of The usage level "dcsa (t140)" has been added to the registration of
the SDP 'inactive' attribute in the "Session Description Protocol the SDP 'inactive' attribute in the "Session Description Protocol
(SDP) Parameters" registry as follows: (SDP) Parameters" registry as follows:
Contact name: IESG Contact name: IESG
Contact email: iesg@ietf.org Contact email: iesg@ietf.org
Attribute name: inactive Attribute name: inactive
Usage level: dcsa(t140) Usage level: dcsa (t140)
Purpose: Negotiate the direction in which real-time text can be sent Purpose: Negotiate the direction in which real-time text can be sent
on a T.140 data channel. on a T.140 data channel.
Reference: RFC 8865 Reference: RFC 8865
10. References 10. References
10.1. Normative References 10.1. Normative References
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[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8373] Gellens, R., "Negotiating Human Language in Real-Time [RFC8373] Gellens, R., "Negotiating Human Language in Real-Time
Communications", RFC 8373, DOI 10.17487/RFC8373, May 2018, Communications", RFC 8373, DOI 10.17487/RFC8373, May 2018,
<https://www.rfc-editor.org/info/rfc8373>. <https://www.rfc-editor.org/info/rfc8373>.
[RFC8826] Rescorla, E., "Security Considerations for WebRTC", [RFC8826] Rescorla, E., "Security Considerations for WebRTC",
RFC 8826, DOI 10.17487/RFC8826, November 2020, RFC 8826, DOI 10.17487/RFC8826, January 2021,
<https://www.rfc-editor.org/info/rfc8826>. <https://www.rfc-editor.org/info/rfc8826>.
[RFC8827] Rescorla, E., "WebRTC Security Architecture", RFC 8827, [RFC8827] Rescorla, E., "WebRTC Security Architecture", RFC 8827,
DOI 10.17487/RFC8827, November 2020, DOI 10.17487/RFC8827, January 2021,
<https://www.rfc-editor.org/info/rfc8827>. <https://www.rfc-editor.org/info/rfc8827>.
[RFC8831] Jesup, R., Loreto, S., and M. Tüxen, "WebRTC Data [RFC8831] Jesup, R., Loreto, S., and M. Tüxen, "WebRTC Data
Channels", RFC 8831, DOI 10.17487/RFC8831, November 2020, Channels", RFC 8831, DOI 10.17487/RFC8831, January 2021,
<https://www.rfc-editor.org/info/rfc8831>. <https://www.rfc-editor.org/info/rfc8831>.
[RFC8864] Drage, K., Makaraju, M., Ejzak, R., Marcon, J., and R. [RFC8864] Drage, K., Makaraju, M., Ejzak, R., Marcon, J., and R.
Even, Ed., "Negotiation Data Channels Using the Session Even, Ed., "Negotiation Data Channels Using the Session
Description Protocol (SDP)", RFC 8864, Description Protocol (SDP)", RFC 8864,
DOI 10.17487/RFC8864, November 2020, DOI 10.17487/RFC8864, January 2021,
<https://www.rfc-editor.org/info/rfc8864>. <https://www.rfc-editor.org/info/rfc8864>.
[T140] ITU-T, "Protocol for multimedia application text [T140] ITU-T, "Protocol for multimedia application text
conversation", Recommendation ITU-T T.140, February 1998, conversation", Recommendation ITU-T T.140, February 1998,
<https://www.itu.int/rec/T-REC-T.140-199802-I/en>. <https://www.itu.int/rec/T-REC-T.140-199802-I/en>.
[T140ad1] ITU-T, "Recommendation ITU-T.140 Addendum 1 (02/2000), [T140ad1] ITU-T, "Recommendation ITU-T.140 Addendum 1 (02/2000),
Protocol for multimedia application text conversation", Protocol for multimedia application text conversation",
February 2000, February 2000,
<https://www.itu.int/rec/T-REC-T.140-200002-I!Add1/en>. <https://www.itu.int/rec/T-REC-T.140-200002-I!Add1/en>.
skipping to change at line 890 skipping to change at line 890
DOI 10.17487/RFC3261, June 2002, DOI 10.17487/RFC3261, June 2002,
<https://www.rfc-editor.org/info/rfc3261>. <https://www.rfc-editor.org/info/rfc3261>.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <https://www.rfc-editor.org/info/rfc3550>. July 2003, <https://www.rfc-editor.org/info/rfc3550>.
[RFC8832] Jesup, R., Loreto, S., and M. Tüxen, "WebRTC Data Channel [RFC8832] Jesup, R., Loreto, S., and M. Tüxen, "WebRTC Data Channel
Establishment Protocol", RFC 8832, DOI 10.17487/RFC8832, Establishment Protocol", RFC 8832, DOI 10.17487/RFC8832,
November 2020, <https://www.rfc-editor.org/info/rfc8832>. January 2021, <https://www.rfc-editor.org/info/rfc8832>.
Acknowledgements Acknowledgements
This document is based on an earlier Internet-Draft edited by Keith This document is based on an earlier Internet-Draft edited by Keith
Drage, Juergen Stoetzer-Bradler, and Albrecht Schwarz. Drage, Juergen Stoetzer-Bradler, and Albrecht Schwarz.
Thomas Belling provided useful comments on the initial Thomas Belling provided useful comments on the initial
(pre-submission) version of the current document. Paul Kyzivat and (pre-submission) version of the current document. Paul Kyzivat and
Bernard Aboba provided comments on the document. Bernard Aboba provided comments on the document.
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