rfc3351.txt

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Network Working Group                                        N. Charlton
Request for Comments: 3351                                      Millpark
Category: Informational                                        M. Gasson
                                                          Koru Solutions
                                                               G. Gybels
                                                              M. Spanner
                                                                    RNID
                                                             A. van Wijk
                                                                Ericsson
                                                             August 2002


      User Requirements for the Session Initiation Protocol (SIP)
                  in Support of Deaf, Hard of Hearing
                    and Speech-impaired Individuals

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

   This document presents a set of Session Initiation Protocol
   (SIP) user requirements that support communications for deaf, hard of
   hearing and speech-impaired individuals.  These user requirements
   address the current difficulties of deaf, hard of hearing and
   speech-impaired individuals in using communications facilities, while
   acknowledging the multi-functional potential of SIP-based
   communications.

   A number of issues related to these user requirements are further
   raised in this document.

   Also included are some real world scenarios and some technical
   requirements to show the robustness of these requirements on a
   concept-level.









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Table of Contents

   1. Terminology and Conventions Used in this Document................2
   2. Introduction.....................................................3
   3. Purpose and Scope................................................4
   4. Background.......................................................4
   5. Deaf, Hard of Hearing and Speech-impaired Requirements for SIP...5
      5.1 Connection without Difficulty................................5
      5.2 User Profile.................................................6
      5.3 Intelligent Gateways.........................................6
      5.4 Inclusive Design.............................................7
      5.5 Resource Management..........................................7
      5.6 Confidentiality and Security.................................7
   6. Some Real World Scenarios........................................8
      6.1 Transcoding Service..........................................8
      6.2 Media Service Provider.......................................9
      6.3 Sign Language Interface......................................9
      6.4 Synthetic Lip-reading Support for Voice Calls...............10
      6.5 Voice-Activated Menu Systems................................10
      6.6 Conference Call.............................................11
   7. Some Suggestions for Service Providers and User Agent
      Manufacturers...................................................13
   8. Acknowledgements................................................14
      Security Considerations.........................................14
      Normative References............................................15
      Informational References........................................15
      Author's Addresses..............................................15
      Full Copyright Statement........................................17

1. Terminology and Conventions Used in this Document

   In this document, the key words "MUST", "MUST NOT","REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
   and "OPTIONAL" are to be interpreted as described in BCP 14,
   RFC2119[1] and indicate requirement levels for compliant SIP
   implementations.

   For the purposes of this document, the following terms are considered
   to have these meanings:

   Abilities:  A person's capacity for communicating which could include
   a hearing or speech impairment or not.  The terms Abilities and
   Preferences apply to both caller and call-recipient.

   Preferences:  A person's choice of communication mode.  This could
   include any combination of media streams, e.g., text, audio, video.





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   The terms Abilities and Preferences apply to both caller and
   call-recipient.

   Relay Service:  A third-party or intermediary that enables
   communications between deaf, hard of hearing and speech-impaired
   people, and people without hearing or speech-impairment.  Relay
   Services form a subset of the activities of Transcoding Services (see
   definition).

   Transcoding Services:  A human or automated third party acting as an
   intermediary in any session between two other User Agents (being a
   User Agent itself), and transcoding one stream into another (e.g.,
   voice to text or vice versa).

   Textphone:  Sometimes called a TTY (teletypewriter), TDD
   (telecommunications device for the deaf) or a minicom, a textphone
   enables a deaf, hard of hearing or speech-impaired person to place a
   call to a telephone or another textphone.  Some textphones use the
   V.18[3] protocol as a standard for communication with other textphone
   communication protocols world-wide.

   User:  A deaf, hard of hearing or speech-impaired individual.  A user
   is otherwise referred to as a person or individual, and users are
   referred to as people.

   Note:  For the purposes of this document, a deaf, hard of hearing, or
   speech-impaired person is an individual who chooses to use SIP
   because it can minimize or eliminate constraints in using common
   communication devices.  As SIP promises a total communication
   solution for any kind of person, regardless of ability and
   preference, there is no attempt to specifically define deaf, hard of
   hearing or speech-impaired in this document.

2. Introduction

   The background for this document is the recent development of SIP[2]
   and SIP-based communications, and a growing awareness of deaf, hard
   of hearing and speech-impaired issues in the technical community.

   The SIP capacity to simplify setting up, managing and tearing down
   communication sessions between all kinds of User Agents has specific
   implications for deaf, hard of hearing and speech-impaired
   individuals.








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   As SIP enables multiple sessions with translation between multiple
   types of media, these requirements aim to provide the standard for
   recognizing and enabling these interactions, and for a communications
   model that includes any and all types of SIP-networking abilities and
   preferences.

3. Purpose and Scope

   The scope of this document is firstly to present a current set of
   user requirements for deaf, hard of hearing and speech-impaired
   individuals through SIP-enabled communications.  These are then
   followed by some real world scenarios in SIP-communications that
   could be used in a test environment, and some concepts of how these
   requirements can be developed by service providers and User Agent
   manufacturers.

   These recommendations make explicit the needs of a currently often
   disadvantaged user-group and attempt to match them with the capacity
   of SIP.  It is not the intention here to prioritize the needs of
   deaf, hard of hearing and speech-impaired people in a way that would
   penalize other individuals.

   These requirements aim to encourage developers and manufacturers
   world-wide to consider the specific needs of deaf, hard of hearing
   and speech-impaired individuals.  This document presents a
   world-vision where deafness, hard of hearing or speech impairment are
   no longer a barrier to communication.

4. Background

   Deaf, hard of hearing and speech-impaired people are currently
   often unable to use commonly available communication devices.
   Although this is documented[4], this does not mean that developers or
   manufacturers are always aware of this.  Communication devices for
   deaf, hard of hearing and speech-impaired people are
   currently often primitive in design, expensive, and non-compatible
   with progressively designed, cheaper and more adaptable communication
   devices for other individuals.  For example, many models of textphone
   are unable to communicate with other models.

   Additionally, non-technical human communications, for example sign
   languages or lip-reading, are non-standard around the world.









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   There are intermediary or third-party relay services (e.g.
   transcoding services) that facilitate communications, uni- or bi-
   directional, for deaf, hard of hearing and speech-impaired people.
   Currently relay services are mostly operator-assisted (manual),
   although methods of partial automation are being implemented in some
   areas.  These services enable full access to modern facilities and
   conveniences for deaf, hard of hearing and speech-impaired people.
   Although these services are somewhat limited, their value is
   undeniable as compared to their previous complete unavailability.

   Yet communication methods in recent decades have proliferated:
   email, mobile phones, video streaming, etc.  These methods are an
   advance in the development of data transfer technologies between
   devices.

   Developers and advocates of SIP agree that it is a protocol that not
   only anticipates the growth in real-time communications between
   convergent networks, but also fulfills the potential of the Internet
   as a communications and information forum.  Further, they agree that
   these developments allow a standard of communication that can be
   applied throughout all networking communities, regardless of
   abilities and preferences.

5. Deaf, Hard of Hearing and Speech-impaired Requirements for SIP

   Introduction

   The user requirements in this section are provided for the benefit of
   service providers, User Agent manufacturers and any other interested
   parties in the development of products and services for deaf, hard of
   hearing and speech-impaired people.

   The user requirements are as follows:

5.1 Connection without Difficulty

   This requirement states:

   Whatever the preferences and abilities of the user and User Agent,
   there SHOULD be no difficulty in setting up SIP sessions.  These
   sessions could include multiple proxies, call routing decisions,
   transcoding services, e.g., the relay service Typetalk[5] or other
   media processing, and could include multiple simultaneous or
   alternative media streams.







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   This means that any User Agent in the conversation (including
   transcoding services) MUST be able to add or remove a media stream
   from the call without having to tear it down and re-establish it.

5.2 User Profile

   This requirement states:

   Deaf, hard of hearing and speech-impaired user abilities and
   preferences (i.e., user profile) MUST be communicable by SIP, and
   these abilities and preferences MUST determine the handling of the
   session.

   The User Profile for a deaf, hard of hearing or speech-impaired
   person might include details about:

   - How media streams are received and transmitted (text, voice, video,
     or any combination, uni- or bi-directional).

   - Redirecting specific media streams through a transcoding service
     (e.g., the relay service Typetalk)

   - Roaming (e.g., a deaf person accessing their User Profile from a
     web-interface at an Internet cafe)

   - Anonymity: i.e., not revealing that a deaf person is calling, even
     through a transcoding service (e.g., some relay services inform the
     call-recipient that there is an incoming text call without saying
     that a deaf person is calling).

     Part of this requirement is to ensure that deaf, hard of hearing
     and speech-impaired people can keep their preferences and abilities
     confidential from others, to avoid possible discrimination or