Subject: Re: [Enum] E.164 communication assumptions/requirements

From: "Stastny Richard" <[email-masked]>
Date: Wed, 27 Jul 2005 16:53:22 -0400

Penn,
 
if you say so.
 
Nevertheless, do not forget that with ENUM calls
may terminate on the PSTN and also on IP (via ENUM)
Do you think the carrier may decide without the user
consent where to terminate the call?
 
-richard
 
------------------------------------------------------------------------ 

Richard:
The ITAC report was not as you interpret it. Opt-in for the calling
entity means there is no duty to query or to use the result if the query
is made. The originator in this clause was NOT restricted to be the end
user but could be the calling user's carrier.
-----Original Message-----
From: Stastny Richard [mailto:Richard.Stastny at oefeg.at <mailto:Richard.Stastny at oefeg.at> ]
Sent: Wednesday, July 27, 2005 4:20 PM
To: Pfautz, Penn L, NEO; James McEachern
Cc: enum at ietf.org
Subject: Re: [Enum] E.164 communication assumptions/requirements

Penn, James,

>So if I understand correctly, a carrier should never query User ENUM
>unless the originating user has explicitly asked the carrier to do the
>query on his behalf, and has also provided guidance on what to do in
>various situations (for example if the query returns a phone number in
>another country, or a "900" number).

Yes

Penn, please re-read the historic "Final Report on ENUM" of the US
ITAC-T
SGA Ad-Hoc, Juli 2001, which was the basis of the US ENUM Forum

It clearly states (I think in section 3.4) that User ENUM is opt-in
BOTH for the CALLING and the called user. So the opt-in
(consent) of the subscriber is necessary to query User ENUM

Now there IS an interesting issue related to ENUM-only numbers

ENUM-only numbers cannot be in carrier ENUM per se because
there is no hosting carrier. A carrier could pretend to be stupid and
route all calls to the PSTN and charge for them.

Now with these numbers there is no obligation for an originating
network on the PSTN to a specific gateway, so the originating
network may directly route the call to his own gateway. This
is the whole idea of such numbers.

Therefore a carreir on IP  also could be "clever", pretend to be a
gateway, query User ENUM, and route the call directly
(charging for it or not)
This does not require opt-in by the calling user !!!

The originating carrier may have a list of all such numbers;
or, for convenience, carrier ENUM may contain a hint!
This is the proposed "enum:tel" Enumservice.

-richard

________________________________

Von: Pfautz, Penn L, NEO [mailto:ppfautz at att.com <mailto:ppfautz at att.com> ]
Gesendet: Mi 27.07.2005 14:09
An: James McEachern; Stastny Richard
Cc: enum at ietf.org
Betreff: RE: [Enum] E.164 communication assumptions/requirements

I would disagree that a carrier can't query user ENUM without explicit
consent of the originating caller. But if a carrier uses the results and
the results are funky in the ways suggested than I would expect the
carrier to eat any added cost *unless* they have some specific terms of
agreement with the originator.
Realistically, carriers are not stupid (well not entirely :-)) and would
distinguish between a SIP URL that would allow them to terminate a call
bypassing the circuit switched network and a redirecting tel URL that
would be a scam.

-----Original Message-----
From: enum-bounces at ietf.org [mailto:enum-bounces at ietf.org <mailto:enum-bounces at ietf.org> ] On Behalf Of
James McEachern
Sent: Tuesday, July 26, 2005 9:27 PM
To: Stastny Richard
Cc: enum at ietf.org
Subject: RE: [Enum] E.164 communication assumptions/requirements

Richard,
Thanks for the clarification - it clears up a couple of questions that
have been confusing me for a while now.

So if I understand correctly, a carrier should never query User ENUM
unless the originating user has explicitly asked the carrier to do the
query on his behalf, and has also provided guidance on what to do in
various situations (for example if the query returns a phone number in
another country, or a "900" number).

Jim

 > -----Original Message-----
 > From: Stastny Richard [mailto:Richard.Stastny at oefeg.at <mailto:Richard.Stastny at oefeg.at> ]
 > Sent: Tuesday, July 26, 2005 1:00 PM
 > To: McEachern, James [CAR:5N00:EXCH]
 > Cc: enum at ietf.org
 > Subject: Re: [Enum] E.164 communication assumptions/requirements
 >
 > James,
 >
 > let me first start with a practical example:
 > Assume I have an Intertex IX67 at home (or a Snom phone)
 > which is capable of querying User ENUM on his own.
 >
 > I enter now a E.164 number and I want to make a voice call.
 > The IX67 find a sip URI in ENUM and the call is set up. Done
 >
 > If the IX67 does not find an entry; it forward the call to a Carrier
 > I have a contract with and this carrier is now querying Carrier ENUM
 > If it find an entry. done. if not the call is routed to the PSTN
 > In both cases I may or may not be charged by the carrier.
 >
 > Now assume I do not have a IX67, I just have a Sipura TA and
 > a normal phone. In this case the call is directly handled by the
 > carrier. The cariier is only quierying Carrier ENUM by default.
 >
 > I may now have a contract with the carrier that the carrier is
querying
 > User ENUM FIRST on my behalf. He may charge me $5 a month for
 > this service, but he does not charge me for the call. The rest is as
 > above.
 >
 > rest inline:
 >
 > >>The end-user queries User ENUM, the Carrier queries Carrier ENUM.
 > >>A Carrier MAY query User ENUM on behalf of the user in addition, if
the
 > >>user wants so (opt-in) and the carrier is providing this service.
 >
 > >If the Carrier queries Carrier ENUM (and retrieves the POI for that
 > number),
 > >and then also queries User ENUM (and receives the URI for the users
 > mobile phone),
 > >what should the Carrier do (and why)?
 >
 > The feasable agreement would be as described above that always User
ENUM
 > is queried
 > first, In this case the Carrier ENUM entry would never be seen
 >
 > >If the User ENUM query returns a phone number in another country,
what
 > should the carrier do?
 >
 > This is a good point and it is not completely solved in User ENUM.
Since
 > User ENUM is also
 > calling user opt-in, it is basically the decision of the calling user
if
 > a PSTN number is accessed at all
 >
 > Remember: if you dial a E.164 number and the number is not contained
in
 > ENUM, you need
 > to have a carrier avaiable to provide you a GW to the PSTN to
complete
 > the call and you will
 > be charged anyway. The problem is as you point out: you may dial a
 > national number
 > and the User ENUM query returns an international number: Do you
forward
 > this number
 > now also to the carrier or not. The basic question here is the
(undefined)
 > user interface:
 > do you get a warning that the call may be more expensive?
 >
 > In the above case you mention IMHO there has to be a prior agreement
 > between user
 > and carrier how the procedure should be in such cases.
 >
 > BTW: we had this problem in implementing the generic gateways for
calls
 > to ENUM-only
 > numbers from the PSTN. Since the call on the PSTN is only charged to
the
 > gateway, there
 > is no way to recover the additional charges from the calling party if
an
 > ENUM entry
 > contains a tel URI to a PSTN number. The solution was that this calls
are
 > not completed
 > with announcement: service not provided. It is strongle recommended
to
 > users of
 > ENUM-only numbers to provide a sip URI in any case.
 >
 > >And finally, if the User ENUM query returns a link to a web page,
what
 > should the Carrier do?
 >
 > Nothing. the user requested a voice call, so he may either look up
 > carrier ENUM or if this also
 > does not work: "Service not available.", same if you see an
ifax:mailto
 > Have you ever had a meaningful conversation with a fax machine on the
 > PSTN? ;-)
 >
 > Jim
 >

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---

From: Otmar Lendl <[email-masked]>
Date: Thu, 28 Jul 2005 07:03:26 -0400

> consent where to terminate the call?

There is a nice non-ENUM related example for such rerouting of calls:

The German incumbent T-Com offers its customers a product called
"Switch&Profit".  (sorry, only german links)

http://www.pcwelt.de/news/vermischtes/115495/
http://www.golem.de/0507/39117.html

The idea is the following:

When T-Com user A wants to call T-Com user B on his mobile (operated by
e.g. Vodafone), then T-Com has to play rather high termination fees to
Vodafone to complete the call. Those costs are of course charged to user
A. [Remember: in Europe it's sender pays all for calls to mobiles. There
are no charges incurring on the receiving side.]

Now, when B is actually at home, there is no need to use the Vodafone
mobile to reach him, calling him on his fixed line is good enough. 
Here is where "Switch&Profit" comes in: if B subscribes to this service
and tells T-Com that he is at home, then T-Com will re-route the call to
B's fixed line. T-Com will still charge A the same $/min, but T-Com does
no longer need to play Vodafone. That profit is shared between T-Com and
B who receives 2.59 cent/min for such calls.

---------------------

As with ENUM, the destination of a call advertises the availability of
an alternative way of completing the call. If it's financially beneficial
for an originating telco to take up this offer, why should it decline to
do so?

The only open issue here is of regulatory nature. In the example from
above: Does Vodafone have a right to receive the call to B even if B 
told T-Com that an alternative is fine with him?

I've no idea whether the legal aspects of this service have been settled yet.

Given http://www.teletarif.de/arch/2004/kw42/s15139.html, it looks
like there have been legal disputes already.

(hehe, and they even have the same validation issue as with user ENUM:
http://www.xdial.de/arch/2004/kw42/s15152.html )

/ol
-- 
< Otmar Lendl (lendl at nic.at) | nic.at Systems Engineer >

---

From: "Peter Williams" <[email-masked]>
Date: Thu, 28 Jul 2005 09:42:41 -0400

As with ENUM, the destination of a call advertises the availability of
an alternative way of completing the call. If it's financially beneficial
for an originating telco to take up this offer, why should it decline to
do so?
The only open issue here is of regulatory nature. In the example from
above: Does Vodafone have a right to receive the call to B even if B
told T-Com that an alternative is fine with him?
ok. Lets sideline the direct issue of this personal/telco profit driver, and 
focus on the indirect infrastructure requirements that flow from such 
incentives. A ENUM convergence strategy CANNOT diminish the effectiveness of 
current regulatory practice in such areas as wiretap:

Court C orders trap and trace and a wiretap on B, for some legitimate 
reason. How do we discover all the parties (VAR, telcos, ISPs, and ENUM 
providers) who might query ENUM (for trap and trace) or actually complete 
the call (for wiretap), so we can present the order?

Not interested now in dealing with the 20% of folks who might use end-end IP 
encryption, or route-hiding based on walled-garden ENUMs, or those who hide 
secret routes in their User ENUM URLs  in the e164.arpa. Lets just focus on 
the 80% of folks who simply subscribe to PSTN-regulated or regulated VOIP 
carriers.

---

From: Jim Reid <[email-masked]>
Date: Thu, 28 Jul 2005 10:13:16 -0400

On Jul 28, 2005, at 14:42, Peter Williams wrote:
Court C orders trap and trace and a wiretap on B, for some legitimate 
reason. How do we discover all the parties (VAR, telcos, ISPs, and 
ENUM providers) who might query ENUM (for trap and trace) or actually 
complete the call (for wiretap), so we can present the order?
I do not understand what point you're making. Or if there even is a 
point. DNS lookups provide a means of finding an end-point for some 
method of communication. This is completely orthogonal to how or even 
if that form of communication is used. Besides, getting the IP 
addresses of whatever looked up this intercepted number is a completely 
different thing from identifying the client which initiated the lookup. 
There's almost always at least one open recursive name server in 
between the originating client and the authoritative name server.

---

From: "Clive D.W. Feather" <[email-masked]>
Date: Thu, 28 Jul 2005 10:46:17 -0400

Peter Williams said:
> reason.

Not in the UK, it doesn't.

> How do we discover all the parties (VAR, telcos, ISPs, and ENUM 

The same problem already occurs with call diversion or number portability.

-- 
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