Subject: Re: [Ecrit] Query: How to derive Emergency Call from SIP INVITE Message

From: [email-masked]
Date: Mon, 3 Mar 2008 08:28:33 +0000

Brian Rosen wrote:
> Generally, the IETF has not spent a lot of time on the specifics of how 
a
> PSAP without an IP connection handles a call that originated in an IP
> network.

Brian, do you actually mean *no* IP connection, or specifically no SIP 
connection?

The UK's work on an architecture for Emergency Location is based on a PSTN 
connection to the PSAP with information identifying the VSP and caller 
carried in SS7.

There is however also an out-of-band IP connection from the VSP to the 
PSAP which carries the source IP address, which is then (by an as yet 
undecided mechanism) mapped to an access network (ISP) LIS, which is in 
turn then interrogated with HELD.

Ray

-- 
Ray Bellis
Senior Researcher in Advanced Projects, Nominet
e: [email-masked], t: +44 1865 332211
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From: "Brian Rosen" <[email-masked]>
Date: Mon, 3 Mar 2008 11:30:35 -0500

The IETF work recognized that there will be nation-specific mechanisms in
place to get calls to PSAPs that don't directly take the signaling specified
in its documents.  Generally, there are no national variations of any
Internet protocol.  If the device, the access network and the calling
network follow the ecrit/geopriv/sip specs, the call will route to some kind
of proxy server (we would call this an "emergency services routing proxy").
That proxy, which can get all the information about the call, can forward
the call to a gateway to any kind of PSAP you may have.

So, in your example, the gateway would provide the SIP to PSTN interwork, as
well as the interwork for the (as yet undecided) mechanism to HELD.

There is some work in NENA along the same lines, interworking new IETF based
devices and networks to older PSAPs.

Brian

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf Of
> [email-masked]
> Sent: Monday, March 03, 2008 3:29 AM
> To: [email-masked]
> Subject: Re: [Ecrit] Query: How to derive Emergency Call from SIPINVITE
> Message
> 
> Brian Rosen wrote: