[Search] [txt|xml|pdf|bibtex] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01                                                         
SLIM                                                           N. Rooney
Internet-Draft                                                      GSMA
Expires: October 7, 2016                                   April 5, 2016

                             SLIM Use Cases


   Use cases for selection of language for internet media.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on October 7, 2016.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Rooney                   Expires October 7, 2016                [Page 1]

Internet-Draft               slim-use-cases                   April 2016

1.  Introduction

   The SLIM Working Group [SLIM] is developing standards for language
   selection for non-real-time and real-time communications.  There are
   a number of relevant use cases which could benefit from this
   functionality including emergency service real-time communications
   and customer service.  This document details the use cases for SLIM
   and gives some indication of necessary requirements.  For each use
   case a 'Solution' is provided, indicating the implementability of the
   use case based on "Negotiating Human Language in Real-Time
   Communications" [NEGOTIATING-HUMAN-LANG].

2.  Use Cases

   Use cases are listed below:

2.1.  Single two-way language

   The simplest use case.  One language and modality both ways in media
   described in SDP [RFC4566] as audio or video or text.
   Straightforward.  Works for spoken, written and signed languages.  An
   example is when a user makes a voice call and the preferred language
   of that user is specified in SDP, allowing the answerer to make
   decisions based on that specification.

   o  Solution: Possible

2.2.  Alternatives in the same modality

   Two or more language alternatives in the same modality.  Two or more
   languages both ways in media described in SDP as audio or video or
   text, but only in one modality.  Straightforward.  Works for spoken,
   written and signed languages.  The answering part selects.  There is
   a relative preference expressed by the order, and the answering part
   can try to fulfill that in the best way.  An example is a user who
   makes a voice call and prefers French as their first language and
   German as their second, and the answerer selects to speak German as
   no French speaking abilites are available.

   o  Solution: Possible

2.3.  Fairly equal alternatives in different modalities.

   Two or more modality alternatives.  Two or more languages in
   different modalities both ways in media described in SDP as audio or
   video or text.  An example is a person with hearing abilities who is
   also competent in sign language declares both spoken and sign
   language competence in audio and video.  This is fairly

Rooney                   Expires October 7, 2016                [Page 2]

Internet-Draft               slim-use-cases                   April 2016

   straightforward, as long as there is no strong difference in
   preference for these alternatives.  The indication of sign language
   competence is needed to avoid invoking relay services in calls with
   deaf sign language users only indicating sign language.

   o  Solution: Possible

2.4.  Last resort indication

   One language in the different modalities.  Allows the user to
   indicate one last resort language when no other is available.  For
   example, a hearing user has text capability but want to use that as
   last resort.  (With current specifications, there is no way to
   describe preference level between modalities and no way to describe
   absolute preference.)

   o  Solution: An answering service will have no guidance to which is
      the preferred modality and may select to use the modality that is
      the callers last resort even if the preferred alternative is

   Another practical case can be a sign language user with a small
   mobile terminal that has some inconvenient means for texting, but
   sign language will be strongly preferred.  In order to not miss any
   calls, the indication of text as last resort would be desirable.

   o  Solution: need coding of an absolute preference: hi, med, lo
      together with the tag.

2.5.  Directional capabilities in different modalities

   Two or more language alternatives in the different modalities.  For
   example, a hard-of-hearing user strongly prefers to talk and receive
   text back.  Spoken language input is appreciated.  This can be
   indicated by spoken language two-ways in audio, and reception of
   language in text.  (There is no current solution that says that the
   text path is important.  The answering part may see it as an

   o  Solution: Need for preference indication per modality

2.5.1.  Fail gracefully?

   There currently are methods to indicate that the call shall fail if a
   language is not met, but that may be too drastic for some users
   including the one in the above scenario (Section 2.5).  It may be
   important to be able to connect and just say something, or use
   residual hearing to get something back when the voice is familiar.

Rooney                   Expires October 7, 2016                [Page 3]

Internet-Draft               slim-use-cases                   April 2016

   o  Possible solution: coding of an absolute preference together with
      the tag could solve this case if used together with the
      directional indications.  For example:

   "preference: hi, med, lo"

   Another solution would be to indicate required grouping of media,
   however this raises the complexity level.

2.6.  Combination of modalities

   Similar to Section 2.5, two or more language alternatives in the
   different modalities.  A person who is deaf-blind may have highest
   preference for signing to the answerer and then receiving text in
   return.  This requires the indication of sign language output in
   video and text reception in text, using the current directional
   attributes.  An answering party may seek suitable modalities for each
   direction and find the only possible combination.

   o  Solution: Need for preference indication per modality

2.7.  Person with speech disabilities who prefer speech-to-speech

   One specific language for one specific modality with a speech-speech
   engine.  A person who may find that others have some difficulty in
   understanding what they are trying to say may be used to have support
   of a speech-to-speech relay service that aids clear speech when
   needed for the understanding.  Typically, only calls with close
   friends and family might be possible without the relay service.

   This user would indicate preference for receiving spoken language in
   audio.  Text output can be indicated but this user might want to use
   this method as a last resort.  (There is no current coding for vague
   or unarticulated speech or other needs for a speech-to-speech

   A possibility could be to indicate no preference for spoken language
   out, a coding of proposed assisting service and an indication of text
   output on a low absolute level.

   o  Solution: Need of service indication, and absolute level of
      preference indication.

Rooney                   Expires October 7, 2016                [Page 4]

Internet-Draft               slim-use-cases                   April 2016

2.8.  Person with speech disabilities who prefer to type and hear

   Two or more language alternatives for multiple modalities.  A person
   who speaks in a way that may be hard to understand, may be used to
   using text for output and listen to spoken language for input.  This
   user would indicate preference for receiving spoken language in
   audio.  Text output modality can be indicated.

   If the answering party has text and audio capabilities, there is a
   match.  If only voice capabilities exist there is a need to invoke a
   text relay service.

   o  Solution: Need of service indication, and absolute level of
      preference indication.

2.9.  All Possibilities

   Mutiple languages and multiple modalities.  For example: a tele-sales
   center calls out and wants to offer all kinds of possibilities so
   that the answering party can select.  A tele-sales center has
   competence in multiple spoken languages and can invoke relay services
   rapidly if needed.  So, it indicates in the call setup competence in
   a number of spoken languages in audio, a number of sign languages in
   video and a number of written languages in text.  This would allow,
   as a further example, a deaf-blind person who prefers to sign out and
   get text back answers with only these capabilities.  The center can
   detect that and act accordingly, this could work in the following

   o  Solution Alternative 1: The center calls without SDP.  A deafblind
      user includes its SDP offer and the center sees what is needed to
      fulfill the call.

   o  Solution Alternative 2: The center calls out with only the spoken
      language capabilities indicated that the caller can handle.

   The person with deaf and / or sight disabilities who answers, or
   terminal or service provider detects the difference compared to the
   capabilities of the answering party, and adds a suitable relay
   service.  (This does not use all the offerings of the callers
   competence to pull in extra services, but is maybe a more realistic
   case for what usually happens in practice. )

   o  Solution: Possible in the same way as cases in Section 1.8.

Rooney                   Expires October 7, 2016                [Page 5]

Internet-Draft               slim-use-cases                   April 2016

3.  Final Comments

   The use cases identified here try to cover all cases of when users
   wish to make text, voice or video communication using the language of
   set of languages in which they are able to speak, write or sign and
   for which the receivers are also able to communicate.  Some of these
   use cases go even further to allow give some users the ability to
   select multiple and different languages based on their abilities and

   To fulfill all the use cases the currently specified directionality
   will be needed, as well as an indication of absolute preference.  An
   indication of suitable service and its spoken language is needed for
   the speech-to-speech case, but can be useful for other cases as well.
   There is no clear need for explicit grouping of modalities seem to be

   Subsequent work in the Selection of Language for Internet Media
   Working Group [SLIM] will work on Internet Drafts to support these
   use cases.

4.  Security Considerations

   Indications of user preferred language may give indications as to
   their nationality, background and abilities.  It may also give
   indication to any possible disabilities and some existing and ongoing
   health issues.

5.  IANA Considerations

   This document has no IANA actions.

6.  Informative References

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", RFC 4566, DOI 10.17487/RFC4566,
              July 2006, <http://www.rfc-editor.org/info/rfc4566>.

   [SLIM]     "SLIM Working Group", n.d.,

              Gellens, R., "Negotiating Human Language in Real-Time
              Communications", 2016, <https://datatracker.ietf.org/doc/

Rooney                   Expires October 7, 2016                [Page 6]

Internet-Draft               slim-use-cases                   April 2016

Appendix A.  Acknowledgments

   Gunnar Hellstrom's experience and knowledge in this area provided a
   great deal of these use cases.  Thanks also goes to Randall Gellens
   and Brian Rosen.

Author's Address

   Natasha Rooney

   Email: nrooney@gsma.com
   URI:   https://gsma.com

Rooney                   Expires October 7, 2016                [Page 7]