Subject: RE: [Ecrit] Issue 30: Summary

From: "Stark, Barbara" <[email-masked]>
Date: Tue, 31 Jan 2006 14:40:14 -0600

Brian said:
I do wonder if some kind of confirmation may be useful if you do have
overlap, just so you don't dial the local emergency number by mistake,
but I think confirmation would be much less error prone than escape for
local emergency number.
 
A confirmation, after you dial the overlapping-with-local-dial-plan
visited emergency number (possibly accidentally), would take longer than
the 4 to 5 seconds of waiting that I proposed. By the way, what language
is the confirmation in? Home or visited?
 
Given that most visitors of the temporarily-visiting kind (not the
ex-pat kind) are absolutely clueless as to the visited emergency number
of wherever they're visiting, it's likely that they won't know to dial a
prefix before an overlapping home string. My mother, brother, and I have
all been to Switzerland many times (and my mother is an ex-pat), but
none of us could tell you what to dial from a landline in case of an
emergency. I don't recall any fire trucks or police cars going by with
numbers written on them, either.
 
I have enough trouble getting it through the thick skulls of my
co-workers that they shouldn't dial 9-1-1 from our building, because the
IP PBX is located 10 miles away. We have a special 10-digit emergency
number to dial. I've sent repeated emails, written articles in our
newsletter, and have stickers available for their phones. And in spite
of all the stickers and notices, the first thing someone did when he
needed to call in an emergency was dial 9-1-1. Fortunately, it's still
inside the same city, so the call was routed correctly.
 
The main problem you're trying to address is the babysitter (what is she
doing in the home office, anyway?), and that's really a corner case. 5
extra seconds for that corner case is not unreasonable. Personally, I'd
much prefer to have a completely predictable home dialing plan, and know
that 9-1-1 always works, than have to try to figure out all visited
emergency numbers and whether or not there's a number thay overlaps my
home dialing plan.
Barbara

-----Original Message-----
From: Brian Rosen [mailto:[email-masked]]
Sent: Tuesday, January 31, 2006 2:35 PM
To: Stark, Barbara; [email-masked]
Subject: RE: [Ecrit] Issue 30: Summary

So, bottom line:

GSM's work because it uses the visited dial plan, with the visited
emergency number.

Roaming VoIP today doesn't work at all for emergency calling, but if it
did work, you assume it must have the home dial plan.

What I'm saying is that the way roaming VoIP should work is that the
home dial plan should be altered to have the visited emergency number,
and any overlap should require an escape mechanism from the merged dial
plan to access.  So, if you are calling someone with a 911 extension
while you are roaming in the U.S., you may need to dial a 6911, or you
may need to dial #911 or something else.

I actually think that is not a problem.  I do wonder if some kind of
confirmation may be useful if you do have overlap, just so you don't
dial the local emergency number by mistake, but I think confirmation
would be much less error prone than escape for local emergency number.

Apply the babysitter test to Henning's German VSP.  There is a phone on
his home office desk.  It is indistinguishable from any other phone in
the house visually.  The babysitter has an emergency and picks it up.
She hears dial tone.  She dials 9-1-1.  It should work, and it should
work right away.  If 911231232 is a legal number in Germany, Henning may
have to dial a prefix to get it.  I think that is the right tradeoff.

Brian

  _____  

From: Stark, Barbara [mailto:[email-masked]] 
Sent: Tuesday, January 31, 2006 2:17 PM
To: [email-masked]; [email-masked]
Subject: RE: [Ecrit] Issue 30: Summary

If you bring a GSM phone into a foreign country, it's the visited
emergency number which will work, and the dialing plan will be local to
where you're visiting.

If you bring a SIP ATA into a foreign country, today, it will have
absolutely no knowledge of the visited emergency number. For a US-based
SIP service (provided by a Voice Service Provider) it will know the home
emergency number (although the actual recognition of the string as an
emergency string will happen at the proxy server, and not at the device
itself -- today's VSP-provided devices don't have special "emergency
recognition" code in their software). However, an emergency call from a
foreign country today will be misrouted, since it will be based on the
static location information the subscriber provided. Since the US VSP
will not provide service without an emegency location for which it is
able to provide emergency service, and US VSPs are only able to provide
emergency routing for a subset of US locations, the location will be
extremely inaccurate.

For SIP ATAs, current behavior, as it stands, is that emergency dialing
does not work when calling from a foreign country. The visited emergency
string isn't recognized at all. Yes, I am proposing that this behavior
be changed. But to try to force GSM-like behavior on a VSP service isn't
reasonable. The expectations of the customer are completely different.
The GSM customer expects their entire dialing plan to change and to
become local to the visited location. The VSP customer (today) expects
their dialing plan to be completely static, independent of where they
visit. The purpose for using a  German VSP service in the US is so that
you can dial German phone numbers locally, and be reached locally from
Germany. This is completely and totally different from the expectations
of the GSM customer.

The GSM customer's dialing plan is always determined by the owner of the
cell tower they're connected to. The VSP customer's dialing plan is
always determined by the same proxy server, no matter where in the world
they are. This means, by the way, that unless the device itself
recognizes the visited emergency number, visited location numbers will
never, ever work for these customers. If the visited emergency dial
string reaches the proxy without having been changed to the SIP
Emergency URI, then the proxy will NOT recognize it as an emergency dial
string. The proxy will only recognize home strings, and the emergency
URI. Because the VSP may not be able to control whether the user's
device can recognize visited emergency numbers, it is likely that VSPs
will instruct customers to always use the home emergency number,
independent of where they are. Furthermore, the VSP would probably tell
the customer that a visited emergency number may or may not work,
depending on the capabilities of the device they are using, and
depending on the capabilities of the LAN and ISP they are connected
through; therefore, absolutely no assurances can be made as to whether
or not the visited emergency number will work.

Barbara 

-----Original Message-----
From: Brian Rosen [mailto:[email-masked]]
Sent: Tuesday, January 31, 2006 12:55 PM
To: Stark, Barbara; [email-masked]
Subject: RE: [Ecrit] Issue 30: Summary

If you would like, I'll raise this with the PSAP and NENA folks.  I
don't think they will agree with you.

The visited emergency number has to work immediately, which means it has
to be recognized by a dial plan, and not depend on timeouts or # key
presses.

I think they would say that the home emergency number could have the
delay or #.

You are proposing to change current behavior; as it stands now, if you
bring a phone into a country, it's the visited emergency number that
works.  I do understand that if you use an enterprise phone from a VPN
or something equivalent, everything breaks (you don't have the local
emergency number, you don't have correct location, and the call goes to
the home psap).   I think we really are better off with "both", even if
that causes some kinds of problems with home dial plans.  It's much
easier to deal with Extension 999 doesn't work as a 3 digit number when
I call from the UK as it does "please remember to hit # or wait 4
seconds" to get help when you are in the middle of London.

Brian

  _____  

From: [email-masked] [mailto:[email-masked]] On Behalf
Of Stark, Barbara
Sent: Tuesday, January 31, 2006 10:44 AM
To: [email-masked]
Subject: Re: [Ecrit] Issue 30: Summary

This seems generally reasonable to me, also. 
However, there is an implicit expectation in the description below that
I'm not quite comfortable with, in the "precedence" statement. That is,
whether or not end of dialing string is automatically recognized for
visited emergency numbers.

For devices that use a "Send" button, this isn't a problem. "Send" must
always be pressed to indicate "end of dialing". For these, there would
be no clash between a US "911" and UK "911xxx" dial string. If the user
enters "911xxx" + "Send", then this must never be interpreted as "911".
Similarly, "911" + "Send" is equally unambiguous (in this example).

SIP devices without a "Send" button generally employ a variety of
mechanisms to recognize "end of dialing". 
 1. Some strings are automatically recognized; for example, when a user
dials any "N11" string and has an ATA configured for US dialing plans,
the ATA recognizes this string and automatically sends the SIP Invite
without waiting any further.

 2. The user can usually press "#" to indicate end of dialing. Many
users are unaware of this fact. 
 3. If the user does not press another digit in 4 or 5 seconds (differs
by device), this is interpreted as end of dialing, and the SIP Invite is
sent.

What this means, is that, if a user enters a string that is not
automatically recognized as being "complete", and the user doesn't press
"#", there will be a 4 or 5 second delay between the time when the last
digit is pressed and SIP signaling begins.

While I realize that this delay is generally undesirable, I would prefer
that there be no requirement to automatically recognize "end of dialing"
for visited emergency strings.

The flip side of this is that if the ATA's current dialing plan has an
automatically escaped string that is shorter than the visited emergency
number (e.g., an ATA might automatically recognize "00" as a complete
string, and the visited emergency number is "000"), then the ATA logic
needs to stop recognizing "00" as a complete string. I'm fine with this.
The user can then dial "00" (+ timeout) or "00#", and also "000" (+
timeout) or "000#".

If done this way, the only clashes would be for exact matches. 
Barbara 
======================================== 
On Jan 28, 2006, at 12:25 PM, Stastny Richard wrote: 

1. By default, the device is set to use the home dialplan 
and home emergency numbers, either directly or via 
the home provider. 
2. If not at home, the device get its location and also 
the visited emergency numbers via some means 
3. The visited emergency numbers take precendence 
over the home dialling plan, if a clash occurs. 
(Note: your home provider may provide you with an 
escape code to override this, but then you definitely know 
what you are doing - e.g. to reach 911xxx local numbers in UK 
if you happen to be in the US.) 
Note: this may cause some emergency calls done wrong, 
but this is preferrable to missroute some real emergency calls 

*****

The information transmitted is intended only for the person or entity to
which it is addressed and may contain confidential, proprietary, and/or
privileged material. Any review, retransmission, dissemination or other
use of, or taking of any action in reliance upon this information by
persons or entities other than the intended recipient is prohibited. If
you received this in error, please contact the sender and delete the
material from all computers. 117

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---

From: "Brian Rosen" <[email-masked]>
Date: Tue, 31 Jan 2006 16:21:56 -0500

We may have to agree to disagree, and we may need some more input.

It takes a whole lot less than 4 seconds to confirm.  The language would
probably have to be visited.  Eventually, the phone will have a real UI and
we can do a lot better.  

Your experience with visiting other countries is much different from mind.
I learn the local emergency number wherever I travel because I might need
it.   The emergency numbers in Switzerland are:

117

Polizei-Notruf <http://www.polizei.ch/> 

Police emergency <http://www.polizei.ch/>  call

Police, appel <http://www.polizei.ch/>  d'urgence

Polizia, chiamata <http://www.polizei.ch/>  di soccorso

117

118

Feuerwehr-Notruf

Fire department emergency call

Feu, centrale d'alarme

Pompieri

118

144

Sanität-Notruf

Ambulance emergency call

Ambulances, appel d'urgence

Pronto soccorso autoambulanze

144

Your example of your IP-PBX is classic, and of course we want to make 9-1-1
work for all of the employees and visitors who it serves.

You may call the babysitter a corner case, I don’t.  It’s the way the world
works now (VoIP is too new, and things don’t work, we’re trying to fix
that).

You may very well dial 9-1-1 in an emergency when you are in Switzerland.
That won’t work the way you expect it to, but we can probably route you to
117.  That’s the corner case.  We should make it “work”, but it’s not really
a requirement.  The requirement is that 9-1-1 works from all phones in North
America, and that 117 works for police for all phones in Switzerland.  

Brian

  _____  

From: Stark, Barbara [mailto:[email-masked]] 
Sent: Tuesday, January 31, 2006 3:40 PM
To: [email-masked]; [email-masked]
Subject: RE: [Ecrit] Issue 30: Summary

Brian said:

I do wonder if some kind of confirmation may be useful if you do have
overlap, just so you don’t dial the local emergency number by mistake, but I
think confirmation would be much less error prone than escape for local
emergency number.

A confirmation, after you dial the overlapping-with-local-dial-plan visited
emergency number (possibly accidentally), would take longer than the 4 to 5
seconds of waiting that I proposed. By the way, what language is the
confirmation in? Home or visited?

Given that most visitors of the temporarily-visiting kind (not the ex-pat
kind) are absolutely clueless as to the visited emergency number of wherever
they're visiting, it's likely that they won't know to dial a prefix before
an overlapping home string. My mother, brother, and I have all been to
Switzerland many times (and my mother is an ex-pat), but none of us could
tell you what to dial from a landline in case of an emergency. I don't
recall any fire trucks or police cars going by with numbers written on them,
either.

I have enough trouble getting it through the thick skulls of my co-workers
that they shouldn't dial 9-1-1 from our building, because the IP PBX is
located 10 miles away. We have a special 10-digit emergency number to dial.
I've sent repeated emails, written articles in our newsletter, and have
stickers available for their phones. And in spite of all the stickers and
notices, the first thing someone did when he needed to call in an emergency
was dial 9-1-1. Fortunately, it's still inside the same city, so the call
was routed correctly.

The main problem you're trying to address is the babysitter (what is she
doing in the home office, anyway?), and that's really a corner case. 5 extra
seconds for that corner case is not unreasonable. Personally, I'd much
prefer to have a completely predictable home dialing plan, and know that
9-1-1 always works, than have to try to figure out all visited emergency
numbers and whether or not there's a number thay overlaps my home dialing
plan.

Barbara

-----Original Message-----
From: Brian Rosen [mailto:[email-masked]]
Sent: Tuesday, January 31, 2006 2:35 PM
To: Stark, Barbara; [email-masked]
Subject: RE: [Ecrit] Issue 30: Summary

So, bottom line:

GSM’s work because it uses the visited dial plan, with the visited emergency
number.

Roaming VoIP today doesn’t work at all for emergency calling, but if it did
work, you assume it must have the home dial plan.

What I’m saying is that the way roaming VoIP should work is that the home
dial plan should be altered to have the visited emergency number, and any
overlap should require an escape mechanism from the merged dial plan to
access.  So, if you are calling someone with a 911 extension while you are
roaming in the U.S., you may need to dial a 6911, or you may need to dial
#911 or something else.

I actually think that is not a problem.  I do wonder if some kind of
confirmation may be useful if you do have overlap, just so you don’t dial
the local emergency number by mistake, but I think confirmation would be
much less error prone than escape for local emergency number.

Apply the babysitter test to Henning’s German VSP.  There is a phone on his
home office desk.  It is indistinguishable from any other phone in the house
visually.  The babysitter has an emergency and picks it up.  She hears dial
tone.  She dials 9-1-1.  It should work, and it should work right away.  If
911231232 is a legal number in Germany, Henning may have to dial a prefix to
get it.  I think that is the right tradeoff.

Brian

  _____  

If you bring a GSM phone into a foreign country, it's the visited emergency
number which will work, and the dialing plan will be local to where you're
visiting.

If you bring a SIP ATA into a foreign country, today, it will have
absolutely no knowledge of the visited emergency number. For a US-based SIP
service (provided by a Voice Service Provider) it will know the home
emergency number (although the actual recognition of the string as an
emergency string will happen at the proxy server, and not at the device
itself -- today's VSP-provided devices don't have special "emergency
recognition" code in their software). However, an emergency call from a
foreign country today will be misrouted, since it will be based on the
static location information the subscriber provided. Since the US VSP will
not provide service without an emegency location for which it is able to
provide emergency service, and US VSPs are only able to provide emergency
routing for a subset of US locations, the location will be extremely
inaccurate.

For SIP ATAs, current behavior, as it stands, is that emergency dialing does
not work when calling from a foreign country. The visited emergency string
isn't recognized at all. Yes, I am proposing that this behavior be changed.
But to try to force GSM-like behavior on a VSP service isn't reasonable. The
expectations of the customer are completely different. The GSM customer
expects their entire dialing plan to change and to become local to the
visited location. The VSP customer (today) expects their dialing plan to be
completely static, independent of where they visit. The purpose for using a
German VSP service in the US is so that you can dial German phone numbers
locally, and be reached locally from Germany. This is completely and totally
different from the expectations of the GSM customer.

The GSM customer's dialing plan is always determined by the owner of the
cell tower they're connected to. The VSP customer's dialing plan is always
determined by the same proxy server, no matter where in the world they are.
This means, by the way, that unless the device itself recognizes the visited
emergency number, visited location numbers will never, ever work for these
customers. If the visited emergency dial string reaches the proxy without
having been changed to the SIP Emergency URI, then the proxy will NOT
recognize it as an emergency dial string. The proxy will only recognize home
strings, and the emergency URI. Because the VSP may not be able to control
whether the user's device can recognize visited emergency numbers, it is
likely that VSPs will instruct customers to always use the home emergency
number, independent of where they are. Furthermore, the VSP would probably
tell the customer that a visited emergency number may or may not work,
depending on the capabilities of the device they are using, and depending on
the capabilities of the LAN and ISP they are connected through; therefore,
absolutely no assurances can be made as to whether or not the visited
emergency number will work.

Barbara 

-----Original Message-----
From: Brian Rosen [mailto:[email-masked]]
Sent: Tuesday, January 31, 2006 12:55 PM
To: Stark, Barbara; [email-masked]
Subject: RE: [Ecrit] Issue 30: Summary

If you would like, I’ll raise this with the PSAP and NENA folks.  I don’t
think they will agree with you.

The visited emergency number has to work immediately, which means it has to
be recognized by a dial plan, and not depend on timeouts or # key presses.

I think they would say that the home emergency number could have the delay
or #.

You are proposing to change current behavior; as it stands now, if you bring
a phone into a country, it’s the visited emergency number that works.  I do
understand that if you use an enterprise phone from a VPN or something
equivalent, everything breaks (you don’t have the local emergency number,
you don’t have correct location, and the call goes to the home psap).   I
think we really are better off with “both”, even if that causes some kinds
of problems with home dial plans.  It’s much easier to deal with Extension
999 doesn’t work as a 3 digit number when I call from the UK as it does
“please remember to hit # or wait 4 seconds” to get help when you are in the
middle of London.

Brian

  _____  

From: [email-masked] [mailto:[email-masked]] On Behalf Of
Stark, Barbara
Sent: Tuesday, January 31, 2006 10:44 AM
To: [email-masked]
Subject: Re: [Ecrit] Issue 30: Summary

This seems generally reasonable to me, also. 
However, there is an implicit expectation in the description below that I'm
not quite comfortable with, in the "precedence" statement. That is, whether
or not end of dialing string is automatically recognized for visited
emergency numbers.

For devices that use a "Send" button, this isn't a problem. "Send" must
always be pressed to indicate "end of dialing". For these, there would be no
clash between a US "911" and UK "911xxx" dial string. If the user enters
"911xxx" + "Send", then this must never be interpreted as "911". Similarly,
"911" + "Send" is equally unambiguous (in this example).

SIP devices without a "Send" button generally employ a variety of mechanisms
to recognize "end of dialing". 
 1. Some strings are automatically recognized; for example, when a user
dials any "N11" string and has an ATA configured for US dialing plans, the
ATA recognizes this string and automatically sends the SIP Invite without
waiting any further.

 2. The user can usually press "#" to indicate end of dialing. Many users
are unaware of this fact. 
 3. If the user does not press another digit in 4 or 5 seconds (differs by
device), this is interpreted as end of dialing, and the SIP Invite is sent.

While I realize that this delay is generally undesirable, I would prefer
that there be no requirement to automatically recognize "end of dialing" for
visited emergency strings.

The flip side of this is that if the ATA's current dialing plan has an
automatically escaped string that is shorter than the visited emergency
number (e.g., an ATA might automatically recognize "00" as a complete
string, and the visited emergency number is "000"), then the ATA logic needs
to stop recognizing "00" as a complete string. I'm fine with this. The user
can then dial "00" (+ timeout) or "00#", and also "000" (+ timeout) or
"000#".

*****

The information transmitted is intended only for the person or entity to
which it is addressed and may contain confidential, proprietary, and/or
privileged material. Any review, retransmission, dissemination or other use
of, or taking of any action in reliance upon this information by persons or
entities other than the intended recipient is prohibited. If you received
this in error, please contact the sender and delete the material from all
computers. 117