Subject: [Ecrit] Location information in emergency session initiation, need for time and accuracy?

From: <[email-masked]>
Date: Thu, 7 Sep 2006 10:57:16 +0300

Hi all,

When establishing an emergency session, a SIP UA may insert its location
information into SIP INVITE as PIDF-LO object. The location information
is used to route emergency session to correct PSAP and if the location
is accurate enough, it can be used to advise the rescue team where
needed. Delay of the emergency session establishment needs to be
minimized and therefore UA may have to use old location information or
provide it later during the call. Would it be beneficial to provide some
kind of time stamp and accuracy information for the location? RFC 4119
(PIDF-LO) does not define accuracy of the location information. It
defines timestamp for presence tuple, which indicates the time of the
last change in the tuple. Maybe that timestamp is enough when geopriv is
the only status element of the tuple but could there be other status
elements in the future? I guess this would be relevant not just for
emergency calls but also for location services in general, where time
and accuracy of the location could be used for many purposes.

How do you people see the relevancy of this kind of additional
information for emergency calls? Would it be worth investigating how to
extend PIDF-LO? There has been some discussion about this also in 3gpp
but no real conclusions.

Br,
	Vesa Hakkarainen
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