Subject: [Ecrit] Issue 30: Summary

From: "Tschofenig, Hannes" <[email-masked]>
Date: Sun, 22 Jan 2006 14:21:25 +0100

hi all, 

i am trying to summarize the discussion related to issue 30/issue 8.  

- there are location-dependent and global emergency identifiers. 
global emergency identifiers are, for example the sos uris introduced in
sipping-sos
draft. location-dependent emergency identifiers are those that are used
today in specific countries (see, for example,
http://www.sccfd.org/travel.html)

- location-dependent numbers might be further categorized into 'home'
emergency numbers (the definition of 'home' relates to a specific user)
and numbers used in a 'local' region (here 'local emergency numbers').
"local" here means the valid emergency telephone number used in the
geographic vicinity the user finds himself in.

- the sip ua should translate home emergency numbers to a global
emergency identifier. the ua is most likely pre-provisioned with this
information to be able to make such a translation.

- there are cases where the sip ua does not recognize the home emergency
number. in this case the home emergency number is not translated to a
global emergency identifier. a sip proxy (in the visited or the home
network) needs to understand that this is an emergency call. 

- the sip ua should translate local emergency numbers to a global
emergency identifier.

- there are scenarios where a user dials a local emergency number that
is different from the home emergency number. the sip user agent might
have no other mechanism to determine whether this is an emergency call
or not. 

henning motivated the usage of local emergency numbers with the
following two examples:

  *  if somebody visits a foreign country and sees a firetruck 
with 999 on the side, he or she expects to be able to dial that number 
and summon that fire truck (or its cousin);

  * There's the "tourist collapses, good samaritan finds tourist cell 
phone and dials local emergency number" case.

there are four approaches to the problem:

1) the sip ua is dynamically configured with local emergency numbers
(whenever the user and the sip user agent travel to a new region) and
therefore the case is not likely to happen
unless you have the following case:

  * Tourist Alice collapses, another tourist Bob finds the cell 
phone of Alice and dials its own home emergency number (because it does
not know the local emergency number) and the home emergency number is
different from the local emergency number and Alice/Bob have different
home emergency numbers.

2) the sip proxy is located in the access network and understands the
local emergency number. 

3) the sip ua is configured to understand all emergency numbers in the
entire world. the sip ua would map these translate all these configured
numbers to global emergency user identifiers. 
the problem is only that local emergency numbers in one region are not
emergency numbers in another region. 

4) the sip ua is not configured to understand all emergency numbers but
the sip proxy is. if we focus on the case where the sip proxy is not
local (otherwise we would again talk about (2)) then there are most
likely the same problems as in (3). 
 
it seems that some of you want to work on a solution for (1) (or have
already worked on it). 

ciao
hannes

ps: the user interface is important to us and we need to be aware of
these aspects (as we need to be aware of many other aspects as well). i
guess that most of you understood what i meant by "out-of-scope". 

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https://www1.ietf.org/mailman/listinfo/ecrit

---

From: Henning Schulzrinne <[email-masked]>
Date: Sun, 22 Jan 2006 11:13:30 -0500

> http://www.sccfd.org/travel.html)

This is probably more nit-picking than substance, but I would avoid  
using the term "identifier" for dial strings such as "9 1 1". Calling  
them 'emergency dial strings' is a bit awkward, but avoids confusion.  
We try to make this distinction in the 2806/3966 RFCs, reserving  
"identifier" to something that has a URI. (Dial strings are not tel  
URIs, for example.)

> geographic vicinity the user finds himself in.

I prefer the term "visited", since this corresponds fairly closely to  
the mobile IP or 3GPP issues using the same terminology.

> information to be able to make such a translation.

For SIP devices, we can probably reference the SIP configuration work  
in this regard, although I wouldn't want to require this. In  
particular, SIP configuration is, unfortunately, fairly heavy-weight.  
It is quite possible for a device to determine its home location and  
then use the same location-to-dial string mapping mechanism that it  
might use for the 'visited' emergency dial string.

> - the sip ua should translate local emergency numbers to a global

I'm guessing that you do mean SHOULD.

> different from the local emergency number and Alice/Bob have different

That seems essentially unsolvable. Given typical tourist herds that I  
have observed, they tend to cluster by nationality (or at least  
region), if only to make the job of the tour guide a bit easier :-)

> emergency numbers in another region.

And, more seriously, emergency numbers in one part of the world are  
used as regular numbers, for services (operator, directory  
assistance, etc.), prefixes or PBX extensions, elsewhere.

> guess that most of you understood what i meant by "out-of-scope".

I think we can, at best, reference some of the potential problems,  
such as the ones that Barbara Stark helpfully pointed out. I suspect  
that these trade-offs may differ a bit for mobile vs. landline devices.

For example, if I'm getting service from the US, but live in  
Australia, it is probably a wise move to give the user of a  
stationary device the option of keeping '00' for international  
operator or using it as an emergency number, following local custom.  
Given that a one or two incidents of "baby sitter dials 9-1-1 on VoIP  
phone and gets no answer" caused major regulatory upheaval in the US,  
I suspect that the default will be to make emergency calls at the  
current location of the device work, even if that interferes with  
some other aspect of the dial plan. It is much better to force the  
user to dial #00 than having a house guest in Adelaide dial 000 to  
get an ambulance and talk to an international operator in New Jersey  
instead.

As always, the IETF does not have the authority to regulate device  
manufacturers. It would be up to local regulatory bodies to give  
standards the force of law or regulation.

Henning

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From: Hannes Tschofenig <[email-masked]>
Date: Sun, 22 Jan 2006 21:06:17 +0100

hi henning,

> "identifier" to something that has a URI. (Dial strings are not tel  

that's fine with me.

> the mobile IP or 3GPP issues using the same terminology.

actually, i thought about using the term 'visited' and then went back to 
the mailing list discussion and followed the suggestion you made in one 
of your previous mails.

in fact, i also thought that the term 'visited' is not quite appropriate 
  here since 'visited' and 'home network' refers to an administrative 
domain rather than a region that happens to use the same emergency dial 
strings.

with the mobile ip terminology it is quitely that you move from one 
visited network to another one but you are still within an area that 
uses the same dial strings.

> might use for the 'visited' emergency dial string.

i also thought about this. it might be possible to use the sip device 
config framework. this aspect was, however, not important for the 
summary of the mailing list discussion.

> I'm guessing that you do mean SHOULD.

yes, if i write it as input for the requirements document.
with this version i just want to get sure that i roughly got the point 
of this discussion.

> That seems essentially unsolvable.

not the entire set of local emergency dial strings is not in any country 
  for another purpose.

> Given typical tourist herds that I  

i tend to agree with you.

> used as regular numbers, for services (operator, directory  assistance, 
> etc.), prefixes or PBX extensions, elsewhere.

yes. that's what i meant.

> I think we can, at best, reference some of the potential problems,  such 
> as the ones that Barbara Stark helpfully pointed out. I suspect  that 
> these trade-offs may differ a bit for mobile vs. landline devices.
> 
> For example, if I'm getting service from the US, but live in  Australia, 
> it is probably a wise move to give the user of a  stationary device the 
> option of keeping '00' for international  operator or using it as an 
> emergency number, following local custom.  Given that a one or two 
> incidents of "baby sitter dials 9-1-1 on VoIP  phone and gets no answer" 
> caused major regulatory upheaval in the US,  I suspect that the default 
> will be to make emergency calls at the  current location of the device 
> work, even if that interferes with  some other aspect of the dial plan. 
> It is much better to force the  user to dial #00 than having a house 
> guest in Adelaide dial 000 to  get an ambulance and talk to an 
> international operator in New Jersey  instead.
> 
maybe this is another topic for the bcp?

ciao
hannes

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From: "Raymond Forbes" <[email-masked]>
Date: Mon, 23 Jan 2006 09:18:14 +0000

Henning,

See point below labelled [rcf]:

Regards,

Ray Forbes.

+44 24 7656 3106 phone
+44 24 7656 3816 fax.
+44 771 851 1361 Mobile/text
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22/01/2006 16:13
 
        To:     "Tschofenig, Hannes" <[email-masked]>
        cc:     [email-masked]
        Subject:        Re: [Ecrit] Issue 30: Summary

[rcf]: GSM Cell Phones address this problem as they can dail a number of 
Emergency numbers from the SIM Card. The Phone can translate the Dialled 
number into the Local Emergency number 112, 911, 110, 111, 000 etc...

Henning

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From: Hannes Tschofenig <[email-masked]>
Date: Mon, 23 Jan 2006 11:15:09 +0100

hi raymond,

~snip~

> number into the Local Emergency number 112, 911, 110, 111, 000 etc...

in gsm there is no equivalent to the global emergency identifier as we 
discuss it here.
as such, you need to have a mechanism to retrieve the local emergency 
numbers in order todo the translation from the home emergency number to 
the local onces.

ciao
hannes