Re: [Ecrit] Emergency Call Framework for Canada; Questions on draft-ietf-ecrit-framework-09

[John Lange <john at johnlange.ca>]

On Tue, 2009-06-02 at 13:42 -0500, James M. Polk wrote:

> clearly a SIP server that doesn't receive location in a 911 call 
> knows to include Ua location if it knows it.

Under the proposed draft-ietf-ecrit-framework, the sip registrar will
never know the location of the end-point and certainly not in time to
route the call to the correct PSAP.

> OBO before the fact means the location information could be 
> stale/old/wrong... this was the argument for using a URI instead of 
> actual location. It seems we can't get away from this little detail.

Yes, it "could be" but that is very unlikely. How often will a device
roam so far from the location it was at when it registered with the VOIP
provider that the cached location can't be used for routing to the
correct ESRP/PSAP? And don't forget that an updated location can still
be queried during the call to erase any doubt.

There will always be examples of where it won't work, wifi on trains and
plains is a good example so they'll have to implement their own location
or we'll have to live with it.

If we wait for a solution that solves every possible scenario then we'll
just have to invent new scenarios ;)

-- 
John Lange
http://www.johnlange.ca