Subject: RE: [Enum] Number Portability Draft

From: "Rosbotham, Paul" <[email-masked]>
Date: Fri, 26 Oct 2001 13:41:38 +0100

Richard

To answer your particular question, I believe that the document is pretty
much technically correct, largely because I assume that James has drawn upon
the earlier work in ETSI Project TIPHON.

I have a few relatively minor comments;

Section 5.4 on Onward routing contains the text "This scheme is also called
Remote Call Forwarding".  I would delete this text.  RCF was very much a
short term expedient whereby customer facilities on GSTN switches were used
to forward calls from the donor network to the customer's new network, hence
giving the illusion of NP.  Onward routing, on the other hand, uses
particular tables which are quite often within the network side of the GSTN
switch databuild.  There are profound differences, because while RCF can
impede the operation of some GSTN features/services, OR does not have such
an impact.

Section 5.5 contains the text "The OR scheme is the least efficient in terms
of using the network resources".  While this is the case when considering
transmission capacity alone (clearly given there are two legs to any call),
the situation is more complex when the network as a whole is considered.
For ACQ, for example, GSTN switch resources are used to perform the NP
query, whether or not the call is to a ported number.  The precise impact of
this varies according to the switch design, and means that for countries
which do not have GSTN switches optimised around IN, querying all calls can
cause a significant overhead, indeed a higher cost than the extra call leg
for that minority of numbers which are ported.  This means that there is a
cross-over point where ACQ is more efficient than OR, driven by the %age of
numbers that are ported, and this cross-over point will vary from country to
country.  The text about efficiency is therefore somewhat trite, and should
be removed.

In Section 7.2, there is a paragraph which commences "Please note that all
those enhancements are for national use".  I would make two points to this
paragraph.  Firstly, it is not a specific European issue, and deserves a
section in its own right.  Secondly, I think the point that needs
re-inforcing in this section is that any NP parameters obtained for a ported
number are only any use in the country where they reside.  To clarify; if a
call to a ported UK number egressed from an IP network into the GSTN in the
USA containing the UK routeing prefix, the call would fail as the prefix is
not internationally significant.  Similarly, if a call to a ported USA
number egressed from an IP network into the GSTN in the UK utilising the
US-LRN for addressing, the call could similarly fail as the parameters are
not designed to be sent internationally.

Hope this is of assistance.

Regards

Paul Rosbotham
Manager, Interconnect Strategy & Technology Regulation
Cable & Wireless plc

Tel :	+44 1344 713246
Fax :	+44 1344 713015
Mob :	+44 7957 805573

> -----Original Message-----
> From:	Richard Shockey [SMTP:[email-masked]]
> Sent:	26 October 2001 04:26
> To:	[email-masked]
> Subject:	[Enum] Number Portability Draft
> 
> 
> As part of our original charter we defined the following. I quote.
> 
> "6. The Working Group will understand the impact of developments in the 
> area of local number portability on the proposed system. "
> 
> the following draft has been offered to describe the current Number 
> Portability status within the GSTN.
> 
> In the opinion of anyone on this list are there any factual or technical 
> errors contained in this draft?
> 
> #############
> 
> A New Internet-Draft is available from the on-line Internet-Drafts
> directories.
> This draft is a work item of the Telephone Number Mapping Working Group of
> 
> the IETF.
> 
>          Title           : Number Portability in the GSTN: An Overview
>          Author(s)       : M. Foster, T. McGarry, J. Yu
>          Filename        : draft-ietf-enum-e164-gstn-np-02.txt
>          Pages           : 26
>          Date            : 22-Oct-01
> 
> This document provides an overview of E.164 telephone number
> portability (NP) in the Global Switched Telephone Network (GSTN).
> There are three types of number portability: service provider number
> portability (SPNP), location portability, and service portability.
> Service provider portability, the focus of the present draft, is a
> regulatory imperative in many countries seeking to liberalize local
> telephony service competition, by enabling end-users to retain pre-
> existing telephone numbers while changing service providers.
> 
> A URL for this Internet-Draft is:
> http://www.ietf.org/internet-drafts/draft-ietf-enum-e164-gstn-np-02.txt
> 
> 
> 
>  >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> Richard Shockey, Senior Manager, Strategic Technology Initiatives
> NeuStar Inc.
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