Subject: [Iptel] Summary of +1-800 for tel URI discussion

From: Henning Schulzrinne <[email-masked]>
Date: Sat, 30 Nov 2002 06:01:46 -0500

Let me try to summarize the +1-800 discussion.

- There are some +1-800 numbers that only work regionally, e.g., in a 
single state or area code. This is not a (major) issue since this is 
similar to other call filtering mechanisms or failures. Context is 
helpful, but not necessary.

- There is no problem with +1-800 numbers 'owned' *by the same 
organization* reaching different terminals or non-800 numbers. This is 
not a URI problem and outside the scope of tel URIs. (There may be 
practical problems if the gateway is located in a different place than 
the caller; somebody ordering pizza in Brooklyn may get connected to the 
PizzaHut in Denver.)

Apparently, there are also some numbers (particularly vanity numbers) 
that are intentionally shared by different organizations (1-800-LAWYER, 
I think). See http://www.hurt911.org/page15-vanity.html or 
http://lawyer-attorney-advertising-marketing.com/1-800-marketing.html

- There may be some +1-800 numbers that are regionally re-used, i.e., 
are re-assigned to completely different entities. Thus, dialing 
+1-800-555-1212 might reach a wedding organizer in Pennsylvania and a 
divorce lawyer in Reno, Nevada. If this number is seen by a gateway 
(and, to a lesser extent, put on a web page), rather unexpected things 
could happen.

Solution: Provide context so that the gateway, which usually knows which 
area code it is in, can decide whether this is valid or not (or a SIP 
proxy can route the request to a gateway where it is valid).

I wonder if anybody has seen a real example of such numbers.

Like all local numbers, one can't avoid certain problems. If a user in 
Nevada clicks on "Divorces" (NV only), but the call is actually handed 
to a gateway in Pennsylvania, you will get the PA version of the number, 
unless the context hints that this number should not be used there.

Thus, I will amend the 2806bis draft to say that freephone numbers in 
countries that allow re-use by different organizations MUST use a 
context indication unless it is known that the number is unique within 
the whole country code. (It does not have to be valid in the whole 
country code.)

Please let me know if I missed any aspect of this discussion or if you 
disagree with the conclusion.

Henning

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From: Rohan Mahy <[email-masked]>
Date: Sat, 30 Nov 2002 10:27:49 -0800

Henning,

1-800-DIENTES or 1-800-LAWYER still qualify as a single organization 
(the referring agency/coorperative/whatever).  Also, nobody has 
demonstrated concretely that any number exists which is orthogonally 
reused (your Nevada divorce/Pennsylvania wedding example).  I expect 
that we can get a definitive answer from NANPA fairly quickly.  I 
really do not want extra language in the spec to handle what I suspect 
is a non-issue, because if folks don't know any better they will litter 
all freephone numbers with context which in most cases is not only 
extraneous, but also in some cases harmful to proper routing.

thanks,
-rohan

On Saturday, November 30, 2002, at 03:01 AM, Henning Schulzrinne wrote:

> the caller; somebody ordering pizza in Brooklyn may get connected to 
> the PizzaHut in Denver.)
>
> that are intentionally shared by different organizations 
> (1-800-LAWYER, I think). See http://www.hurt911.org/page15-vanity.html 
> or 
> Solution: Provide context so that the gateway, which usually knows 
> which area code it is in, can decide whether this is valid or not (or 
> a SIP proxy can route the request to a gateway where it is valid).
>
> to a gateway in Pennsylvania, you will get the PA version of the 
> number, unless the context hints that this number should not be used 
> there.
>

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From: Henning Schulzrinne <[email-masked]>
Date: Sat, 30 Nov 2002 13:51:57 -0500

I agree. I had indeed considered 1-800-LAWYER as an example of the 
PizzaHut variety, even if my grouping of cases did not make this very 
clear. Are you asking NANPA?

Rohan Mahy wrote:

> that we can get a definitive answer from NANPA fairly quickly.  I really
> do not want extra language in the spec to handle what I suspect is a
> non-issue, because if folks don't know any better they will litter all
> freephone numbers with context which in most cases is not only

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From: Scott Bradner <[email-masked]>
Date: Sat, 30 Nov 2002 14:54:23 -0500 (EST)

> I really do not want extra language in the spec to handle what I suspect

I guess I must be confused about this issue - I would have thought that
one needed locational context to resolve 1-800-hot-pizza (or
whatever dominos country-wide number is) in order to direct a call
to the right place (one on N-thousand local shops)

it would seem to be a database loading issue if that number gets paid for
by one or more organizations and not an issue of what information you
need to get to the right place

Scott

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From: Henning Schulzrinne <[email-masked]>
Date: Sat, 30 Nov 2002 15:09:20 -0500

Scott,

trying to guess at the source of confusion here. I suspect that part of 
the problem might be two meanings of the word 'context':

- Context = 'resolve this identifier under this context' 
(;context=+1-212-939-7000 = Pizza Hut as if dialed from 212-939-7000)

- Context = 'this number is only valid if dialed from this context; it's 
an error otherwise' (the number may still reach something or other, but 
it's not the intended destination)

I think most of us are thinking of the second use, not the first. Your 
paragraph seems to hint at the first. Thus, for PizzaHut, there would be 
no need for context (the number is valid, albeit routed differently 
everywhere in the +1 context.) The problem I have with the first 
interpretation is that the context is unknown, since the routing can 
depend on any prefix and can never be known by the writer of a web page, 
say.

I suspect that the PizzaHut routing problem is basically unsolvable as 
soon as you have gateways; you'll always reach the PizzaHut closest to 
the gateway, not the IP-based caller. The routing algorithm is 
presumably based on more than just digits in the ANI phone number. The 
problem is essentially the same as the 911 routing problem; maybe 
Intrado can start a new line of business :-)

However, I'm still not sure I understand your concern.

Now, do I get a PizzaHut coupon?