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Re: [Enum] PBX-to-PBX Internet trunking success with ENUM andh.323 - a first

  • To: Michael Haberler < >
  • From: "Conroy, Lawrence (SMTP)" < >
  • Date: Tue, 16 Sep 2003 10:52:35 +0100
  • Cc:

Hi Folks,
Me too, but using SIP :) All get checked in ENUM before processing. Works fine.

The reason I follow up here is that I note that ENUM code and the configuration systems
that are coming out to populate the ENUM entries need some work. We can standardise
processing in the (I sure hope soon to be) RFC, but what's out there in the field is
not necessarily what we've agreed.

I've seen 2916-compatible entries, 2916bis entries, some strange unregistered ones
(either in 2916 or in 2916bis order/syntax), and multiple entries with the same
order and priority.

Also, I note that the processing code for some boxes treats only the first NAPTR it
handles as the "one to return", regardless of order and priority.

Thus these corner cases (multiple NAPTRs, mixed syntax, unregistered enumservices)
will occur. Even if "your" ENUM entries are correct, the client box that does the
ENUM lookup may not behave quite the way one expects, so - be careful out here.

Whilst it isn't a standards issue, I think that we are getting to the point where
interworking test sessions would be useful.

all the best

At 3:38 pm +0200 6/9/03, Michael Haberler wrote:
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in the preparation for the VoiP/ENUM Tutorial at RIPE-46, we had a little H.323 ENUM <proprietary term from a MN-based company> interworking test.

Participating were the Asterisk Linux IP PBX in Vienna, and the ISDN/IP PBX in Germany. Asterisk was massaged by Otmar Lendl who had just implementend H.323 ENUM lookup in the Asterisk call processing. Martin Streller of Innovaphone is the implementor of the ENUM code in their PBX.

Martin and Otmar got transparent Internet trunking with ENUM to work between an Asterisk and an IP-3000 - you dial a number with a DDI extension on the other PBX as you normally would - NO ACCESS CODES OR TRUNK PREFIXES!! - as there's an ENUM entry and both PBXes do ENUM DNS queries in outbound call processing the call is delivered via IP (h.323 in their case).

An interesting aspect of the Innovaphone device is the fact that it can do drop & insert - it has a network-side and a user-side ISDN port; if you plug it between the telco line and a vanilla PBX, it can act as a least cost routing device based on ENUM lookups - on outbound calls coming from the PBX, it will lookup the number in the DNS and divert to the Internet - otherwise the call will go to the telco in the upstream port. Which means that your old PBX could use ENUM in & outbound unchanged.

I would expect this to become more widespread as PBXes with IP & ENUM clue appear on the market.

BTW Innvoaphone has a very elegant scheme were configuring an extension i the PBX automatically produces a corresponding DNS entry - the PBX itself also acts as an ENUM DNS server for the pilot number and extensions. Currently their boxes are h.323 only but they plan to implement a SIP stack as well.


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