Re: [Enum] Re: URI Portability

Otmar Lendl <> Wed, 08 February 2006 17:48 UTC

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Date: Wed, 08 Feb 2006 18:48:11 +0100
From: Otmar Lendl <>
Subject: Re: [Enum] Re: URI Portability
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On 2006/02/08 18:02, wrote:
> Richard,
> I must be missing something.  As far as I know, individually-owned 
> or company-owned domain names ARE portable.  I can have any service 
> provider run a web server for my domain.  I can have a separate 
> provider handle my email.  I can have lots of providers handle lots 
> of different services for me, and I can switch any particular 
> service from any provider to any other at any time. 
> What kind of portability isn't already implemented?  What portability 
> functions are you looking for that aren't available today?

Have you ever asked one of the new SIP based VoIP outfits (Vonage,
SIPhone, Gizmo, VoIPbuster, SIPgate, ...) whether their system
copes with customers wanting to use their own domain for the
SIP URIs these services use?

I haven't seen that yet. 

The protocol support ist there, no question. But in term of
implementation we're at the level of email anno 1992 where
most people had to use user@provider as their email address.

To make things even more interesting: have a look at the the IMS and all
the other NGN efforts. From what I have heard, these people don't want
to rely on the public DNS for any of their call routing decisions. They
can easily build their own private DNS on their GRX (or whatever)
network and store the domains of the carriers in there.

I can't see how such a private DNS infrastructure can ever cope
with people wanting to user their own domains in an IMS or NGN
setting. Either you duplicate the public DNS in your walled
garden or you abandon your "never depend on the public Internet

So: There is a real chance that for the near future people will 
have no choice but use sip:user@provider as their SIP address.

I thus consider it not _that_ unlikely that regulators will
step in and force portability for such addresses.

Summary: Right now, E.164 numbers are still the primary addressing
mechanism for most SIP/VoIP services. Once that starts to change
and people start to put SIP addresses on their business cards,
then all providers MUST offer the option of using a customer-owned

Failing to support that early can spell trouble down the road.

< Otmar Lendl ( | Systems Engineer >

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