Subject: RE: AW: [Iptel] FW: [Enum] Summary on NoPSTN dicussion

From: "Pfautz, Penn L, ALABS" <[email-masked]>
Date: Thu, 01 Apr 2004 16:57:04 -0500

If I understand it the root issue is this:
All E.164 numbers will have a PSTN point-of-interface, but for some numbers that POI is a gateway to IP. Further some subset of these numbers are ones that won't be assigned if they're not reachable through IP. So, in order to avoid routing to the default gateway after an ENUM query that returns no result because the number is unassigned, people are seeking some mechanism to provide a response to the initial ENUM query to indicate that attempts to route through the PSTN will be fuitless. And the need is to do this without treading on the opt-in principle.

Here's a thought which the more DNS/DDDS literate may be able to confirm or shoot down:
At Tier 1, instead of populating an NS record with the tier 2 delegation for each number instead populate a pair of non-terminal NAPTR records with different service fields (e.g.,  E2U  and E2C) which would point to the domains for the end user Tier 2 and carrier Tier 2 respectively. In this way, a single query would provide pointers into both trees and a client could decide whether to pursue one or the other, or potentially both. For non-assigned "ENUM-only" numbers, the carrier could populate the E2C record only without treading on the perogatives of the end user or having to instantiate a separate Tier 1.
Such E2C records could not only address the NoPSTN issue but also be the basis for a carrier or infrastructure ENUM capability that may become more important as VoIP moves beyond arbitrage to where IP interconnection becomes norm.

Penn Pfautz

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of
Stastny Richard
Sent: Thursday, April 01, 2004 2:36 AM
To: Michael Hammer
Cc: James McEachern; [email-masked]
Subject: AW: AW: [Iptel] FW: [Enum] Summary on NoPSTN dicussion

Mike wrote:

	>>First, no number is owner by anybody, it is assigned by ITU-T to the NRA,
	>>and assigned in turn to the SP, and the SP assignes it to the end-user (for
	>>geographic numbers. Service numbers are already assigned one-by-one
	>>to the end-user by the NRA, no blocks, no anchor SP.
	
	>How does this work for numbers that were assigned to an SP, that used to be
	>TDM-only, but then (over time) converts to an IP-only network?  The SPs are
	>very guarded about the E.164 numbers assigned to them.  That is what I
	>meant by "owned."  You are suggesting that when a person with a phone
	>number assigned by an SP moves to an IP-based "phone" that the SP will
	>relinquish that phone number back to the NRA?  Or are you saying that
	>number portability doesn't work between TDM and IP worlds?
	 
	We are talking here about four different things here:
	Case 1:  a VoIP provider is also an ILEC (eg a cable operator) and gets a 
	number (geographic) range (block) assigned and assignes them to his users.
	Since number assignement is technology independent, there is no problem here,
	as long as the SP is providing a telephony service as usual (we call this PATS -
	Publicly Available Telephony Service in Europe).
	Note: some VoIP SP hide between small ILECs and get such number ranges
	via them (e.g Vonage, sipgate.de, ...)
	 
	Case 2: Since all normal rules apply, also LNP applies, so users may port
	their numbers back and forth between PSTN and VoIP SP
	 
	Case 3: The regulator reserves a special number range for VoIP (050 in
	Japan, 05x in UK, 032 in Germany). If these services are declared non-PATS
	NP does not apply (this is under discussion). In Japan there is also a lighter 
	regime regarding QoS. Regulations differ here in all countries. 
	In this case the VoIP SP also get blocks of numbers and route them to their GW. 
	I know, in the US there is no such number range. The problem I have with
	such an approach is that there are differnt rules in every country and end-users
	get restricted services. (e.g no NP, no access to emergence services, etc.
	IMHO this will cause problems in the future
	 
	Case 4. the regulator reserves a special number range for ENUM-only routed 
	numbers. This should be done directly to the end-user. The advantage is
	that you have NP built-in, without having to deal with normal LNP issues and
	technology, saving the SP much effort.
	 
	The difference between case 3 and 4 is that in case 3 no rules exist for NP and
	interconnect on IP, so you create VoIP Island that are interconnected only via
	the PSTN per default. If you interconnect on IP, you can do this only currently
	with bilateral agreements. In case 4 you have automatically NP and also interconnect
	because you can use ENUM also on IP to interconnect. This is BTW also drafted
	in the SIP Forum Service Provider WG Interconnect Consensus.

	>>With ENUM-only numbers there is no need to assign blocks of numbers.
	>>An ENUM-only number is the equivalent of a domain name. It is assigned
	>>to the end-user directly, who chooses the SP, like with a service number.
	>>You also do not assign domain names in blocks.
	
	>I think there is an issue here.  If the SPs hold most of the current NPA
	>blocks, and there is a migration of many users from TDM to IP, then do you
	>lengthen the number to 11 digits to get more, or do the SPs have to
	>relinquish numbers?

	This a typical NANP problem. In the NANP there is only geographic area
	codes (with the exception of 800 numbers). In most other country there are
	more number types: you have geographic and non-geographic numbers.

	Non-geo numbers are eg mobile numbers, personal numbers, etc. The advantage
	here is that you relieve the pressure on the number exhaust here. Since geo
	numbers are given away in blocks, you have a lot of unused numbers.
	Eg in Austria the geo numbers are using up a great chunk of the numbers:
	we have 1100 4-digit area codes used be appox 4 Mio subscribers,
	on the other hand, we have 5 (five) 3-digit mobile number ranges
	used by 4,5 Mio subscribers (80% of them are behind 2 mobile "area" codes).

	The reason is simple: the mobile number ranges are flat. So if we give eg
	one 3-digit number range to ENUM, we can instantly use them with
	additional 7-digits for 9.999.999 subscribers. 
	
	regards

	Richard

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---

From: Michael Hammer <[email-masked]>
Date: Fri, 02 Apr 2004 12:19:01 -0500

This sounds reasonable to me, but I would rather hear from the DNS experts.

My assumption, as you note below, was that if the number was not in ENUM, 
then the only element that knows whether the number is assigned and 
reachable is the operator PSTN-IP GW that has a configured translation or 
knows that the number is unassigned.

Mike

At 12:11 PM 4/1/2004 -0500, Pfautz, Penn L, ALABS wrote:
If I understand it the root issue is this:
All E.164 numbers will have a PSTN point-of-interface, but for some 
numbers that POI is a gateway to IP. Further some subset of these numbers 
are ones that won't be assigned if they're not reachable through IP. So, 
in order to avoid routing to the default gateway after an ENUM query that 
returns no result because the number is unassigned, people are seeking 
some mechanism to provide a response to the initial ENUM query to indicate 
that attempts to route through the PSTN will be fuitless. And the need is 
to do this without treading on the opt-in principle.

Here's a thought which the more DNS/DDDS literate may be able to confirm 
or shoot down:
At Tier 1, instead of populating an NS record with the tier 2 delegation 
for each number instead populate a pair of non-terminal NAPTR records with 
different service fields (e.g.,  E2U  and E2C) which would point to the 
domains for the end user Tier 2 and carrier Tier 2 respectively. In this 
way, a single query would provide pointers into both trees and a client 
could decide whether to pursue one or the other, or potentially both. For 
non-assigned "ENUM-only" numbers, the carrier could populate the E2C 
record only without treading on the perogatives of the end user or having 
to instantiate a separate Tier 1.
Such E2C records could not only address the NoPSTN issue but also be the 
basis for a carrier or infrastructure ENUM capability that may become more 
important as VoIP moves beyond arbitrage to where IP interconnection 
becomes norm.

Penn Pfautz

-----Original Message-----

        We are talking here about four different things here:
        Case 1:  a VoIP provider is also an ILEC (eg a cable operator) 
and gets a
        number (geographic) range (block) assigned and assignes them to 
his users.
        Since number assignement is technology independent, there is no 
problem here,
        as long as the SP is providing a telephony service as usual (we 
call this PATS -
        Publicly Available Telephony Service in Europe).
        Note: some VoIP SP hide between small ILECs and get such number 
ranges
        via them (e.g Vonage, sipgate.de, ...)

        Case 2: Since all normal rules apply, also LNP applies, so users 
may port
        their numbers back and forth between PSTN and VoIP SP

        Case 3: The regulator reserves a special number range for VoIP 
(050 in
        Japan, 05x in UK, 032 in Germany). If these services are declared 
non-PATS
        NP does not apply (this is under discussion). In Japan there is 
also a lighter
        regime regarding QoS. Regulations differ here in all countries.
        In this case the VoIP SP also get blocks of numbers and route 
them to their GW.
        I know, in the US there is no such number range. The problem I 
have with
        such an approach is that there are differnt rules in every 
country and end-users
        get restricted services. (e.g no NP, no access to emergence 
services, etc.
        IMHO this will cause problems in the future

        Case 4. the regulator reserves a special number range for 
ENUM-only routed
        numbers. This should be done directly to the end-user. The 
advantage is
        that you have NP built-in, without having to deal with normal LNP 
issues and
        technology, saving the SP much effort.

        The difference between case 3 and 4 is that in case 3 no rules 
exist for NP and
        interconnect on IP, so you create VoIP Island that are 
interconnected only via
        the PSTN per default. If you interconnect on IP, you can do this 
only currently
        with bilateral agreements. In case 4 you have automatically NP 
and also interconnect
        because you can use ENUM also on IP to interconnect. This is BTW 
also drafted
        in the SIP Forum Service Provider WG Interconnect Consensus.

        >lengthen the number to 11 digits to get more, or do the SPs have to

        This a typical NANP problem. In the NANP there is only geographic 
area
        codes (with the exception of 800 numbers). In most other country 
there are
        more number types: you have geographic and non-geographic numbers.

        Non-geo numbers are eg mobile numbers, personal numbers, etc. The 
advantage
        here is that you relieve the pressure on the number exhaust here. 
Since geo
        numbers are given away in blocks, you have a lot of unused numbers.
        Eg in Austria the geo numbers are using up a great chunk of the 
numbers:
        we have 1100 4-digit area codes used be appox 4 Mio subscribers,
        on the other hand, we have 5 (five) 3-digit mobile number ranges
        used by 4,5 Mio subscribers (80% of them are behind 2 mobile 
"area" codes).

        The reason is simple: the mobile number ranges are flat. So if we 
give eg
        one 3-digit number range to ENUM, we can instantly use them with
        additional 7-digits for 9.999.999 subscribers.

        regards

        Richard

z{x%^zm?0'~ffX)ߣ

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