[Devel] [ openser-Patches-1344272 ] Carrier ENUM support according to draft-haberler-carrier-enu

Otmar Lendl lendl at nic.at
Tue Oct 10 12:41:03 CEST 2006

On 2006/10/10 12:10, Juha Heinanen <jh at tutpro.com> wrote:
> Otmar Lendl writes:
>  > >  > http://www.ietf.org/internet-drafts/draft-ietf-enum-combined-00.txt
> i went through that one fast and one thing bothers me: how can this
> infra enum be in the public tree?  operators don't like the idea that
> people can check which operator currently handles a particular number,
> because it will give a glue to spammers that the number is active.

If you want to make I-ENUM a private tree then you'd have to define who
should have access to that tree. As the entrance barrier to being an
ITSP is rather minimal (What do you really need besides an OpenSer box,
a Database, a SIP/TDM gateway and someone who provides you with a SS7
uplink?), the numbers of "carriers" have ballooned recently.

(See e.g. http://eurotelcoblog.blogspot.com/, quote:
 I then asked for a show of hands of people who had heard of RTC
 Factory, and only one person raised his hand, but then again he was the
 one who introduced me to the company in the first place, so this was
 no surprise. Quite a few people seemed to shake their heads in smiling
 shock and awe when I repeated the company's claim that it can give
 you (or anyone who can pay) a telco in a box with eight weeks' lead
 time. If investors like to see markets which enjoy significant barriers
 to entry, then this ain't one of them.

There might be solutions on a national level where the regulator steps
in and defines who should have access to that tree. We're living in a
globalized world, thus these national trees won't work unless they are
anchored to a unique global root. That leads to the question on whether
your Finnish telco will let some small ITSP from the Philippines access
the .fi I-ENUM tree.

I thus don't think that any private tree can ever become the single,
dominant global I-ENUM directory. There may well dozens of local and
fabric-specific ENUM trees.

In the current telco world, security by obscurity just doesn't work any
more. The time when there was only one telco per country, are gone. Any
system which relies on the old trust model "I trust all other telcos" is

Regarding knowing which number is active: The Austrian ENUM trial
uses dns wildcards to cover whole number blocks as allocated by the
regulator. There is thus no more information about individual numbers
in there as already made public at the regulator's website.  (One
difference, though: ported numbers will show up.)

Regarding spammers: We don't make the assumption
that SIP URIs as published in I-ENUM resolve to
an open SIP proxy on the public Internet. See
draft-lendl-domain-policy-ddds-02, draft-lendl-speermint-federations-03,
and draft-lendl-speermint-technical-policy-00 for our proposal on how
peering decisions and routing can be tied to the domain of a SIP URI.

An implementation of these ideas as OpenSer module is available
here: http://www.enum.at/index.php?id=dokumente

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

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