Subject: [sipping] Emergency Call Text medium

From: "Gunnar Hellstrom" <[email-masked]>
Date: Tue, 11 Nov 2003 11:52:04 -0600

The status of the Emergency Call Design Team activities was presented today
in the Sipping group.

The needs of deaf and hearing impaired users to be able to communicate with
emergency services in text, was very briefly touched.

This is an apparent need that has its own set of requirements and solutions
and needs to be properly expanded when the work on Emergency Services
progresses. Too many times, late introduction of requirements to access
Emergency services in text mode has resulted in a lot of work and not as
good solutions as if it was specified from the beginning.

Some points for consideration:

1. The requirement to access Emergency Services in character by character
text conversation is described in the new Text over IP draft:
draft-manyfolks-sipping-toip-00.txt

2. The main way to transmit text conversation in SIP sessions shall be by
starting a media stream for text. RFC2793 describes a transport for that. A
proposed revision draft-hellstrom-avt-rfc2793bis-02.txt gives sdp examples
for invoking the text stream. It can exist in parallell with any other
media, as audio.

3. The scope of the current Emenrgency Call work is focused on a
PSTN-located Emergency Service. Therefore, conversion of the text transport
in SIP to the PSTN forms of text telephony must take place in a text-aware
gateway.

4. The status overview of the Emergency Call work mentioned some problems
related to today´s handling of emergency text calls in PSTN.

4.1 Some textphone systems do not give any audible indication of their type,
when they are calling, but sit silent waiting for the called party to issue
the right text modem signals. That is problematic for Emergency Services.
The V.18 standard for text telephony that can automode to all regional text
telephone systems issues audible and machine detectable signals indicating
its text nature. It seems therefore wise to mandate use of V.18 in SIP -
PSTN gateways going to the Emergency services.

4.2 Some countries have separate PSTN numbers for text users. After an
investigation if they are planning to harmonize numbers, it could be studied
if it can be brought into the routing logic of the Emergency Call spec to
call the text number when the Sip call is initiated in text - althought this
must be carefully thought through.

Looking forward to further co-operation between the Sipping Text over IP and
the Emergency Call Design teams.

Regards

Gunnar
-------------------------------------------
Gunnar Hellström
Omnitor AB
Renathvägen 2
SE 121 37 Johanneshov
SWEDEN
+46 8 556 002 03
Mob: +46 708 204 288
www.omnitor.se
[email-masked]
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From: "James M. Polk" <[email-masked]>
Date: Tue, 11 Nov 2003 12:59:30 -0600

Gunnar

As a co-chair (with Brian Rosen) of the NENA VoIP WG - I can assure you 
that group is looking at supporting deaf and hearing impaired users from 
the beginning (which is only 4 months old now).  NENA's intention is to 
generate requirements for IP delivery of emergency services in two groups:

1 - a Migration WG which is for situations in which there is an IP to/from 
TDM transition

and

2 - an End to End IP WG (called the Long Term Definition  or LTD WG)

The requirements coming from NENA will be directed to SIP(PING) (and maybe 
other WGs within the IETF if appropriate) to work on further

Both NENA WGs will work on your suggestions - and I look forward to your 
involvement to further this effort.

Any other requirements you feel need to be met - please forward them to 
Brian and me, as we will take each into NENA for their consideration.

>the Emergency Call Design teams.

cheers,
James

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