Subject: Re: [Ecrit] ECRIT support for TTY/TDD calls

From: [email-masked]
Date: Wed, 15 Feb 2006 21:18:03 EST

I have a question on what is being discussed. Are you only discussing  
TTY/TDD devices used via PSTN specifically by deaf to access emergency services?  
Wanting to clarify that you are not discussing any text user access beyond that, 
 since that could be used by anyone to access emergency services and so 
should  have no special TTY/TDD type handling.
 
Thanks for assistance.
 
Rick Jones
 
In a message dated 2/15/2006 7:47:33 PM Eastern Standard Time,  
[email-masked] writes:

So the UA must know this?  Not the  proxy...?
 
-Marc-

____________________________________
 From: [email-masked]  [mailto:[email-masked]] On Behalf Of 
Brian  Rosen
Sent: Wednesday, February 15, 2006 6:17 PM
To:  'Gunnar Hellstrom'; [email-masked]; 'Aquil, Kamran'; 'François D.  
Ménard'
Cc: 'Gregg Vanderheiden'
Subject: RE: [Ecrit]  ECRIT support for TTY/TDD calls

All I get out of  this for ecrit is that we need entries for sos.police.tty 
in the service  registry 
Brian 

____________________________________
 
From:  Gunnar Hellstrom [mailto:[email-masked]] 
Sent: Wednesday, February 15, 2006 5:47  PM
To: [email-masked];  'Aquil, Kamran'; [email-masked]; François D. Ménard
Cc: Gregg Vanderheiden
Subject: RE: [Ecrit] ECRIT support for  TTY/TDD calls
 
It is quite widely  accepted now that real-time text transmitted with its own 
text coded  RTP payload RFC 4103 is used to carry text that may be gatewayed 
to/from  TTY/TDD/textphones in PSTN.

It is discussed in  
_http://www.ietf.org/internet-drafts/draft-ietf-sipping-toip-03.txt_ 
(http://www.ietf.org/internet-drafts/draft-ietf-sipping-toip-03.txt) 

And it is  documented in 
_http://www.ietf.org/internet-drafts/draft-sinnreich-sipdev-req-08.txt_ 
(http://www.ietf.org/internet-drafts/draft-sinnreich-sipdev-req-08.txt) 

Also other  standardisation bodies have picked up the real-time text concept 
in IP  networks, and pointed at RFC 4103 (or its compatible predecessor 
RFC2793 ).  E.g. 3GPP and ETSI.
 
A couple of years  ago we had an intensive discussion in the SIMPLE mail list 
about the  possibility to use MSRP to carry the real-time text medium, but we 
concluded  that it would cause too much overhead or too much delay for the 
users, so  that RTP was recommended instead. The most common use of MSRP is to 
not  transmit until end of sentence, while for real time text, transmission is  
required with at most 500 ms interval as long as there is anything to  
transmit in order to maintain the real-time feeling of being in touch in a  
conversation through this medium.

Quite commonly you  will connect a text RTP stream and an audio RTP stream 
and possibly a video  RTP stream in the same call, so that you will get an 
enhanced multimedia  phone call with all supported media 

The ecrit requirements also  mentions this correspondence
 
in _www.ietf.org/internet-drafts/draft-ietf-ecrit-requirements-03.txt_ 
(http://www.ietf.org/internet-drafts/draft-ietf-ecrit-requirements-03.txt) 

Re4.   Multiple Modes: Multiple communication modes, such as  audio,
video and text messaging MUST be  supported.

Motivation: In PSTN, voice  and text telephony (often called TTY or
textphone in North America) are the only  commonly supported media.
Emergency  calling must support a variety of media.  Such  media
should include voice, conversational  text (RFC 4103 [9]), instant
messaging and  video.

I am working in a  European group where one of the goals is to agree on 
handling text  users'  requirements on emergency calling in IP networks. Of course 
we  want to agree on global solutions if  possible.

Address mapping is  one important and tricky question for text users. It is 
true that different  countries have different approaches on emergency calling 
with PSTN Text  telephones (TTYs). Some have the same number as voice users, 
while others  have specific numbers. On the SIP side it would be good to have 
the  same URL and make any required routing based on declared media, mode  and 
language capabilities and preferences.  

Text capable  gateways are not at all as common as VoIP gateways, so if the 
PSAP is still  in PSTN, there is a need to have a good mechanism for routing 
emergency  calls from SIP into PSTN through a text capable gateway. I cannot say 
that  the mechanisms for finding the right gateway and make the proper 
address  mapping to a PSTN number is solved yet for the text calls, and it would be  
excellent if we could have that topic in mind in the discussions and get  
proper methods documented.

I have drafted, but  not yet submitted a registration of a SIP URL and an 
ENUM subservice for  real-time text. It might be helpful for finding text 
gateways  and mapping addresses and (text) numbers, but I would like to see  some 
scenarios thoroughly discussed before adding SIP URL and another ENUM  subservice.

Would there be  any benefit of being allowed to enter TXP:112    or  having 
ENUM to find an appropriate address if I   call  112 from a SIP multimedia 
phone declaring text capabilities  with m=text in sdp?

Gunnar
 
-----------------------------------------------------------------------------
 
Gunnar Hellström,  Omnitor
 
[email-masked] (mailto:[email-masked]) 

-----Original  Message-----
From:  [email-masked] [mailto:[email-masked]]On Behalf Of 
François D.  Ménard
Sent: Wednesday,  February 15, 2006 5:14 PM
To: [email-masked]; 'Aquil, Kamran';  [email-masked]
Subject:  Re: [Ecrit] ECRIT support for TTY/TDD calls 

I made a  contribution to CISC NTWG on use of SIP for transporting TDD  
traffic:

_http://www.crtc.gc.ca/cisc/COMMITTE/N-docs/NTCO0338.doc_ 
(http://www.crtc.gc.ca/cisc/COMMITTE/N-docs/NTCO0338.doc) 

I  think it may be relevant to ECRIT.

-=Francois=-

On  2/15/06 10:51 AM, "Brian Rosen" <[email-masked]>  wrote: 
Within the scope  of our work, I don’t see how TDD services are impacted 
until we get to the  architecture effort, which probably has to have some sections 
on that  subject.
With respect to the mapping protocol, I do not believe there  is any impact 
at all.
With respect to the sos service urn, I do not  believe there is any impact at 
all

Ecrit doesn’t have scope  to talk about any kind of gateways or codec support.

Ah!  My BCP on phones and proxies may need some mention, although this is  
the IETF, and I don’t think the ploy of forcing the entire PSTN to support  TDD 
just so 9-1-1 TDD will work.  That effort would have to be in the  general SIP 
 arena.

Brian
 
____________________________________
 
From:  [email-masked] [_mailto:[email-masked]]_ 
(mailto:[email-masked]])   On Behalf Of Aquil,  Kamran
Sent: Wednesday,  February 15, 2006 10:31 AM
To: [email-masked]
Subject: [Ecrit] ECRIT support for  TTY/TDD calls

Folks,

Like to  know if there are specific ECRIT requirements recognizing support 
for  Telecommunications Device for  the Deaf (TDD) services for the hearing 
impaired. If not is this left for  VOIP/SIP gateways to perform this requirement 
of translating the TDD calls  to Text and Speech encoding. Wanted to make sure 
how ECRIT meet  requirement for TDD services.

Regards,
Kamran  Aquil
Intelligent Transportation Systems- Division
Mitretek  Systems.

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--  
Francois D. Menard
[email-masked]

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