Subject: RE: [Ecrit] E911 security issues

From: "Winterbottom, James" <[email-masked]>
Date: Mon, 21 Nov 2005 16:53:15 -0600

Tom,

To be clear are you expecting these data to be measured and maintained
by a proxy making use of an LCMS or the such like, for example a
call-server of some sort? If so I understand how you might keep them,
but I am not sure how you would convey this data to the PSPA gateway
proxy except by possibly introducing a new SIP header or the like *runs
for cover*.

I guess I am not sure how you would maintain this information in the
case where the client went straight to an LCMS and determined the
destination itself. I think that there is a clear difference here, and
we probably need to make the two scenarios obvious in terms of what
options and safe guards can be taken.

Cheers
James

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf
Of
> Tom-PT Taylor
> Sent: Tuesday, 22 November 2005 8:41 AM
> To: Nate Wilcox
> Cc: [email-masked]
> Subject: Re: [Ecrit] E911 security issues
> 
> Obvious criteria are no location in signalling, location in signalling
> not in PSAP jurisdictional area, no authenticated identity.
> 
> Getting more sophisticated, it might or might not be worthwhile to
> identify repeated calls from the same caller or address within the
last
> 24 hours.  Depending on how high the flagging threshold is, repeated
> calls may increase call priority or, past a certain point which should
> be set high enough, be a fairly clear sign of misuse.
> 
> Nate Wilcox wrote:
> > Tom,
> >  You stated:
> >  " (1) Ensure that it provides all the information that could
possibly
> be
> > useful in automated analysis of incoming calls, so that questionable
> calls
> > can at least be flagged when they are presented to the call taker."
> >  Could you elaborate on how this automated analysis "could" work?
> >  Nate Wilcox
> > 802.748.5503
> >
> 
> 
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From: Henning Schulzrinne <[email-masked]>
Date: Mon, 21 Nov 2005 18:09:38 -0500

My assumption would be that the proxy serving the PSAP or a group of 
PSAPs would tabulate this information and then label calls based on 
their probability of being inadvertent, malicious or otherwise suspect.

Labeling can be done in any number of ways, from something simple like a 
request URI like

sip:[email-masked]

to a new P- header. This information is only used within a single trust 
domain, so it doesn't have to be standardized. This is not fundamentally 
different from the various spam filter headers that email MTAs add to 
messages today, without great difficulty. Maybe later, we'll develop 
general content labeling headers for spam/spit control and this work 
might apply here as well.

Henning