Subject: RE: [Sipping] Expert review of draft-ejzak-sipping-p-em-auth-00.t xt

From: "Hadriel Kaplan" <[email-masked]>
Date: Tue, 18 Apr 2006 21:10:04 -0400

Inline...

> -----Original Message-----
> From: Michael Hammer (mhammer) [mailto:[email-masked]]
> Sent: Tuesday, April 18, 2006 7:52 PM
> 
> You missed the point.  Rounding up to nearest half hour meant you get
> charged minimum 30 minutes x $10 or $300.  Are you not aware of the
> incidents where people called 800 numbers only to be forwarded to 900
> numbers that charged them by the minute?  Those folks were surprised
> when it showed up on the bill and the carriers said hey you enjoyed the
> call, so pay up.  It took quite a few complaints before such shenanigans
> were overcome.  The problem here is that there is financial incentive
> for the "UAS" to get the "UAC" side to make the connection, so they can
> be charged.  They aren't interested in grace periods.  Don't aid and
> abet them.

I'm not sure how that is germane to this header use.  If a UAS owner wants
to charge, and doing so merely involves sending a 200ok, then that's totally
under the UAS' power - regardless of what the called number is and who
called it.  I fail to see how playing early media at the UAC helps the UAC
stop that, if the UAS truly wants to charge.  Why would the UAS even bother
sending early media if it did not really wish to help avoid the charges?
Just so it can say "we tried to warn you"?  Under your scenario they were
charging 900 rates for an 800 number. (yes, I've heard it happens) I'd
rather not give them a fake leg to stand on - that would be aiding and
abetting.  There are too many cases where early media doesn't work anyway.

People have already pointed out a provider can charge for early media if
they're worried about fraud.  So there is no recourse to stop the charging
without the provider wishing to.  The point of this draft is to give them a
way of safely playing early media without charging.  IF the provider is the
one doing the 900-charging, and the UAS wants to help avoid charges, then
they can either use a provider which lets them send early media for free, or
ask the provider to be granted such grace period, or use this draft's
header. 

-hadriel

_______________________________________________
Sipping mailing list  https://www1.ietf.org/mailman/listinfo/sipping
This list is for NEW development of the application of SIP
Use [email-masked] for questions on current sip
Use [email-masked] for new developments of core SIP

---

From: Paul Kyzivat <[email-masked]>
Date: Wed, 19 Apr 2006 10:16:06 -0400

Michael Hammer (mhammer) wrote:

> Sorry, went back and read it real slowly.  I think I was thrown by the
> "request in response" language and thought the "request" referred to was
> the INVITE request.  Anyway, the wording might be easier to follow if it
> was phrased as the UAS is asserting an authorization by including the
> header, while any upstream (since this is a response) node may remove
> the header or modify it and thus deny or constrain the authorization to
> an acceptable level.
> 
> BTW, assuming this might pass through more than one domain, does the UAS
> ever know what ultimately is authorized and whether it can send early
> media or expect to receive any forward media?  Seems like a one-sided
> handshake.

This last is a point that I want to reiterate. As currently structured,
the effect is that early media will most likely fail except when the UAS
has special privileges that are recognized not only by its own provider,
but transitively all the way back to the UAC. And there is no mechanism
in place for the UAS to know that is the case.

So there is no way for the sender of early media to have any confidence
that it will work.

Admittedly, even without this header there are cases where early media
may not work. But use of this header has the potential to drastically
increase the set of cases where early media won't work.

Seems like we ought to be working to make early media work better rather
than to make it work worse.

	Paul