Subject: [Sipping] Feedback on draft-ietf-sipping-e164-00.txt

From: "Robert H. Walter" <[email-masked]>
Date: Mon, 3 Dec 2001 17:21:52 -0500

Hi Ben,

> The resulting URI MUST be resolved according to the normal SIP
> address resolution rules. A SIP application MUST ignore a resulting
> URI if the service field does not contain a service it understands.
> Since the only schema that are universally understood by SIP user
> agents are "sip" and "tel", URIs with service fields other than
> "sip+E2U" and "tel+E2U" SHOULD NOT be present in DNS for the purpose
> of being used by a SIP UA.

The first sentence of this paragraph is well stated.  The last
sentence unnecessarily constrains the use of the NAPTR service field.
There are multiple communication services (e.g. Voice, SMS, Voice
Messaging, etc.) that may benefit from SIP interoperability and the
ability for a client UA to address an end-point for the specific
service using an E.164 number.

See the following I-D for more details:

Abstract

  This document describes a set of ENUM resolution protocols and
  services that enable communication applications to interoperate with
  and unambiguously differentiate between multiple communications
  services associated with an E.164 telephone number.

http://www.ietf.org/internet-drafts/draft-walter-ranalli-enum-service-01.txt

Bob

======================================================================
Robert H. Walter - CTO, VP Engineering                tel:+19788482831 
NetNumber, Inc.                                       fax:+19784545044
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---

From: Richard Shockey <[email-masked]>
Date: Mon, 03 Dec 2001 21:17:25 -0500

>service using an E.164 number.

well on this point I totally disagree... there is no reason to create 
granularity in ENUM resolution by SIP through the use of the service 
field... SIP is totally capable of negotiating capabilities of endpoints 
without hints.

this draft is correct is one point there is one SIP service field ..that is 
SIP + E2U SMTP is another case.

Richard Shockey, Senior Manager, Strategic Technology Initiatives
NeuStar Inc.
45980 Center Oak Plaza   Bldg 8     Sterling, VA  20166
1120 Vermont Ave NW Suite 400 Washington DC 20005
Voice 571.434.5651 Cell : 314.503.0640,  Fax: 815.333.1237
<mailto: [email-masked]> or
<mailto: [email-masked]>
<http://www.neustar.biz>
<http://www.enum.org>
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

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From: Ben Campbell <[email-masked]>
Date: 06 Dec 2001 16:59:15 -0600

Hi Bob,

> service using an E.164 number.

I think you are reading more of a constraint into this language than I
intended. I was thinking of SIP UA as a software role that understands
sip: and tel: URLs. If they want to resolve them via DNS, they would use
the sip+e2u or tel+e3u respectively. If you put other service field
values in, you would have no reason to expect the SIP UA to every see
them.

That in no way prevents you from writing software that combines the SIP
UA role with knowledge of additional URL schemes ("foo:" for example)
and also looks for a foo+e2u service field value. But you could not
expect generic SIP UAs to support them.