Subject: [Ecrit] PSAP Call Backs

From: "Tschofenig, Hannes (NSN - FI/Espoo)" <[email-masked]>
Date: Wed, 31 Dec 2008 12:21:24 +0200

Hi all, 

In the last few months we have seen increased interest in the topic of
PSAP call backs. 

Section 10 of  http://tools.ietf.org/html/draft-ietf-ecrit-phonebcp-06
says:

   SP-36 Call backs to the Contact: header URI recieved within 30
   minutes of an emergency call must reach the device regardless of call
   features or services that would normally cause the call to be routed
   to some other entity.

More importantly, Section 13 says: 

   ED-73 Call backs SHOULD be determined by retaining the domain of the
   PSAP which answers an outgoing emergency call and instantiating a
   timer which starts when the call is terminated.  If a call is
   received from the same domain and within the timer period, sent to
   the Contact: or AoR used in the emergency call, it should be assumed
   to be a call back.  The suggested timer period is 5 minutes.

http://tools.ietf.org/id/draft-patel-ecrit-sos-parameter-01.txt proposed
another solution based on marking the callback using the "sos" URI
parameter. 

http://tools.ietf.org/wg/ecrit/draft-ietf-ecrit-local-emergency-rph-name
space/ proposes another solution by utilizing the Resource Priority
Header. 

So, here are my high-level questions: 

A) Do you think that you understand the requirements that lead to a need
for a technical solution? 

B) Do you believe that more work beyond the mechanism described in Phone
BCP is needed? 

Ciao
Hannes
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