Subject: [Ecrit] Henning's comments on -phonebcp

From: "Rosen, Brian" <[email-masked]>
Date: Mon, 19 Nov 2007 09:48:00 -0500

Prof Schulzrinne send me a marked up, scanned in edit of -phonebcp.  I
made most of the edits requested.  There was a couple I did not do:

1. Henning and one or two other commenter's don't like my coarse
location (<1KM).  First of all, there is no real source for the 1 KM.  I
made it up.  What you want is something with a high enough accuracy that
the call will usually route to the right PSAP when you are near a
boundary.  It will never be 100% accurate.  I needed to supply some
useful advice.  I picked a number.  I have modified this text slightly
(typically <1km except when hiding location). 

2. On ED-27, about the frequency of refresh, Henning asked for text
discussing that civic location may be an indication that the device is
not mobile.   Devices can be mobile and report civic.  WiFi devices
reporting the location of an AP may very well report civic.  I did not
change the text.

3. Henning raised some questions about default location.  I changed the
text to refer to -framework which does discuss this.  Generally, it's
"best you can do" and -framework uses the example of the location of a
CMTS in a cable modem system.  I'd welcome suggestions to improve this;
it's an important area.

4. Notwithstanding Hannes' questioning of un-initialized device text,
Henning raised the issue at ED-44 of how an un-initialized device
determines if local regulation requires support of emergency calling.  I
think this is a good question.  I suspect we need something returned
from LoST that tells it.  Discussion on this point is welcome. 

5. Several commenters have questioned the discussion of proxy
determination of local dialstrings.  I have improved the text in this
area, but suggestions for further improvement would be welcome.  A
system like IMS with a home/visited network, where the visited network
provides the proxy work.  Systems where the service provider has a
relationship with the access network and thus the service provider
always has location available work.  This is a severe limitation; many
systems can't meet it, which means they should get the endpoint to do
the dial plan interpretation.  I think the text says that, but
improvement is probably useful.

6.  Henning added the comment "dubious" to the text "User agents and
proxies MUST Support Session Timer [RFC4028] to guard against session
corruption."
I do think we should have it.  Henning, what is the "dubious" part.  I
can downgrade "guard against" to something milder if you are pointing
out that session timers won't reliably determine session corruption.  I
can change corruption to some other term.

7. I'd ask Henning to expand on the "confusing" comment on ED-64 and the
"don't understand" comment on ED-68.  On the latter, the prior
requirement is disabling of features on call backs.  ED-68 is how you
determine a call back, which I propose is simply a call from the same
domain as the PSAP that answered the original emergency call.

8.  I'd also like a little more information on the "check spec" comment
on ED-76.  Which spec am I checking for what?

Brian

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