Urgent: RTT note in WebRTC 1.0


WebRTC 1.0 is expected to reach CR within days. As discussed at our
joint meeting during TPAC[1], we are in agreement to incorporate an
Informative Note section in their specification highlighting the
importance of supporting a specific (IETF specified) Real Time Text
(RTT) protocol which is being mandated through regulatory action for telecommunications carriers
in the U.S. primarily in support of communications with individuals who
are deaf or hard of hearing, and especially for their ability to
communicate with emergency services.

At the same time we are mindful that WebRTC needs to support additional
real time text use cases which might clash with the IETF specified

We are seeking language, therefore, that captures existing support for
RTT as well as the expected ability for future WebRTC specifications to
also support additional use cases.

Herewith is the language proposed by WebRTC for our consideration:

> Subject: 	RTT note in WebRTC 1.0
> Date: 	Wed, 25 Sep 2019 08:43:10 +0200
> ...
> Accessibility considerations [New section, informative]
> The WebRTC 1.0 specification exposes an API to control protocols
> (defined within the IETF) necessary to the establishment of real-time
> audio, video and data exchange.
> Real-time Text, defined in RFC 4103 and on which among others, people
> with disabilities rely on for their communication needs, utilizes T.140
> encapsulated in RTP to enable the transition from TDD/TTY devices to
> IP-based communications.
> Since Real-time Text requires the ability to send and receive data, it
> is best supported via the WebRTC 1.0 data channel API. As defined by
> the IETF, the data channel protocol utilizes the SCTP/DTLS/UDP protocol
> stack, which supports both reliable and unreliable data channel. The
> IETF chose to standardize SCTP/DTLS/UDP over proposals for an RTP data
> channel which relied on SRTP key management and were focused on
> unreliable communications.
> Since the IETF chose a different approach than the RTP data channel as
> part of the WebRTC suite of protocols, as of the time of the publication
> of the WebRTC 1.0 specification, there is no standardized way for the
> WebRTC APIs to directly support Real-time Text.
> Within the IETF MMUSIC WG, work is ongoing to enable Real-time text to
> be sent over the WebRTC data channel, allowing gateways to be deployed
> to translate between the SCTP data channel protocol and RFC 4103
> Real-time text. This work, once completed, would enable a unified and
> interoperable approach for integrating real-time text in WebRTC
> user-agents (including browsers) - through a gateway or otherwise.
> MMUSIC-T140:
> https://tools.ietf.org/html/draft-holmberg-mmusic-t140-usage-data-channel
> ------------------
> Dom
> 1. https://www.w3.org/2019/09/20-apa-minutes.html#item02


Janina Sajka

Linux Foundation Fellow
Executive Chair, Accessibility Workgroup:	http://a11y.org

The World Wide Web Consortium (W3C), Web Accessibility Initiative (WAI)
Chair, Accessible Platform Architectures	http://www.w3.org/wai/apa

Received on Wednesday, 2 October 2019 16:01:58 UTC