Subject: RE: [Ecrit] Best Current Practice for Communications Services insupport of Emergency Calling

From: "McCalmont, Patti" <[email-masked]>
Date: Fri, 3 Mar 2006 15:01:37 -0600

What a great start to our Best Current Practice document. Thanks for
taking the initiative to get it started. I have a few comments:

Page 2 -    "3.  User device includes location indication in the call
set-up
       Messaging"
<PLM> This would be a good place to clarify location indication as
follows
   "3.  User device includes location indication (by reference or by
value) in the call set-up messaging"

   As a quick overview for a typical Ethernet connected telephone using
   SIP signaling:
   o  the phone would get location <indication> from the DHCP server, L7
      server or network access Server when it boots.
   o  It would use "urn:service:sos" as the URI of an emergency call.
   o  It would put its location <indication, if by value in a PIDF-LO or
in   a Location header if by reference,> in the SIP INVITE and forward
the call to its first hop proxy.

So anywhere it talks about getting the location it could be changed to
"location indication", perhaps a definition up front along with the
first usage would help.

   For devices that operate on a network where the network operator does
   not control the specification of every device connected to the
   network, DHCP [or L7] MUST be supported on the network.

<PLM> There are many references to DHCP [or L7]. I would suggest
changing these to, a mechanism must be supported to provide the Location
Indication to the device. There are other methods being proposed for
obtaining location and that should really be up to the access network. I
don't disagree that we should provide some of the options that are
available.

It is desirable that location information be periodically refreshed.

   For devices which are not expected to roam, refreshing on the order
   of once per day is recommended.  For devices which roam, refresh of
   location should be more frequent, with the frequency related to the
   mobility of the device.  There can be instances in which a device is
   aware of when it moves, for example when it changes access points.
   When this type of event occurs, the device should refresh its
   location.

<PLM> For mobile devices, if by reference is not used, there needs to be
a lot of consideration to traffic on the network to refresh the
location. Consider the millions of mobile devices out there and the
impact to all the servers in the path that must refresh the mobile
user's location, say every 5 minutes. The real question that may need to
be asked is, is it necessary to refresh location or only when needed,
like invoking a service that requires location?

Section 6.1    "It is RECOMMENDED that location by-value is used by the
device to convey location during emergency calling."

<PLM> I don't believe we can make this recommendation without doing some
traffic studies. I also don't agree with this recommendation as location
by reference has a lot of value as well.

Patti

-----Original Message-----
From: Tschofenig, Hannes [mailto:[email-masked]] 
Sent: Monday, February 27, 2006 8:44 AM
To: [email-masked]
Subject: [Ecrit] Best Current Practice for Communications Services
insupport of Emergency Calling

Hi all, 

here is another draft:

Best Current Practice for Communications Services in support of
Emergency Calling
http://www.ietf-ecrit.org/cache/draft-rosen-ecrit-phonebcp-00.txt  

   Requesting help in an emergency using a communications device such as
   a telephone or mobile is an accepted practice in most of the world.
   As communications devices increasingly utilize the Internet to
   interconnect and communicate, users will continue to expect to use
   such devices to request help, regardless of whether or not they
   communicate using IP.  The emergency response community will have to
   upgrade their facilities to support the wider range of communications
   services, but cannot be expected to handle wide variation in device
   and service capability.  The IETF has several efforts targeted at
   standardizing various aspects of placing emergency calls.  This memo
   describes best current practice on how devices and services should
   use such standards to reliably make emergency calls

Ciao
Hannes

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