Subject: [Enum] Overlap dialing, again

From: Sören Nyckelgård <[email-masked]>
Date: Mon, 21 Jun 1999 16:23:24 +0200

At the ENUM meeting in Adelaide, the overlap dialing issue was rised again.
The specific issue was that the lenght of the number might not be known by
the client, thus forcing the client to query the DNS for every new digit
entered by the user. In this case we assume that the call is made from a
terminal, like a conventional black phone, that does not require an
'end-of-number' kind of button to be pushed to complete the number.

The chairs were not aware of this particular hazle so the suggestion was to
bring up the issue on the list again. So, here it comes...

Would it be possible for the DNS to, in some way, drop a hint of the length
of the number, e.g. exact length or a minimum length, in order to avoid
querying the DNS inbetween every digit?

 / Sören Nyckelgård, Telia Research

_______________________________________________
enum mailing list
[email-masked]
http://www.ietf.org/mailman/listinfo/enum

---

From: "Manfredi, Albert E" <[email-masked]>
Date: Tue, 28 Mar 2000 09:51:54 -0500

When does the appliance decide to query the DNS? Does the appliance not have
to append the "e164.int" to the phone number before the query is sent?
Somehow, doesn't this imply that the complete number has been entered,
before the query?

Or are you saying that if the user is slow at entering digits, the appliance
might send out multiple DNS requests? Interesting twist.

Bert
[email-masked]

> -----Original Message-----
> From: Sören Nyckelgård [mailto:[email-masked]]
> Sent: Monday, June 21, 1999 10:23 AM
> To: [email-masked]
> Subject: [Enum] Overlap dialing, again
> 
>

---

From: "Lind, Steven D, ALARC" <[email-masked]>
Date: Tue, 28 Mar 2000 10:27:22 -0500

I would assume that "an appliance," smart enough to perform the front end of
the enum functionality, would have some sort of local directory function
that would already contain the complete E.164 number. A "dumb" terminal,
i.e., a plain old telephone, would attach through some network (e.g., the
PSTN) to a gateway. The existing dialing plan and associated timeouts would
govern the progress of the call to the gateway, where the enum functionality
would occur after receiving the complete E.164 number.

If there is a dumb phone attached to an IP access network (e.g., cable
telephony), then the interface to the IP access network would have to
simulate the dialing plan/timeouts existing as general practice or standards
within the specific geopolitical area.

Steve Lind

---------------------------------------------------------------
Steven D. Lind                   Tel: (973) 236-6787
AT&T                             Fax: (973) 236-6452  
180 Park Ave., Bldg. 2            e-mail: [email-masked]
Florham Park, NJ 07932                 
---------------------------------------------------------------

> From:	Manfredi, Albert E [SMTP:[email-masked]]
> Sent:	Tuesday, March 28, 2000 9:52 AM
> To:	'Sören Nyckelgård'; [email-masked]
> Subject:	RE: [Enum] Overlap dialing, again
>

---

From: "Vaudreuil, Greg M (Greg)" <[email-masked]>
Date: Tue, 28 Mar 2000 19:08:22 -0600

In the GSTN, most switches support two types of digit analysis, I will call
them deterministic and non-deterministic.  For the local/in-country dial
plan, the switch has a list of valid prefixes, the expected number of digits
to collect, and any digit translations necessary to "fully qualify" the
number.  This table maps from the dialed number (such as a private dial
plan) into a unique national/international number.  This prefix list varies
switch-to-switch (and often within a switch) based on the local dialing plan
in effect for the caller.  With this list, a number can be determined to be
invalid before all the digits are entered.

For out-of-country telephone numbers, an international escape code is dialed
which simply informs the switch that the local digit analysis rules do not
apply.  The switch then collects digits until either a time-out or a pounds
termination is dialed.  

In Internet space, it is somewhat unreasonable for end-node clients to
independently administer a local copy of the often-changing national dialing
plan.  Further, I  suggest that dialing-time, digit-by-digit validation over
a network protocol will be excessively taxing on both the server and the
client.  I definitely recommend against using DNS to provide this function.
If local dial-plans must be supported, either to eliminate the time-out or
pre-validate a dialed number, they should be provided by the local client,
using a standardized and downloadable digit-analysis configuration file
(such as a web proxy list).   

Greg V.

-----Original Message-----
From: Lind, Steven D, ALARC [mailto:[email-masked]]
Sent: Tuesday, March 28, 2000 9:27 AM
To: 'Manfredi, Albert E'; 'Sören Nyckelgård'; [email-masked]
Subject: RE: [Enum] Overlap dialing, again

Steve Lind

---

From: "Vaudreuil, Greg M (Greg)" <[email-masked]>
Date: Thu, 30 Mar 2000 16:31:34 -0600

It is important to note that the determination of digit length is
application specific. What is fixed-length in PSTN calling is not
necessarily so in telephone addressed messaging.  

In the telephone network, the E.164 sub-address is not generally dialed.
The E.164 sub-address is variable length from 0-4 digits in addition to the
directory number.  In PSTN calling, extension numbers are generally entered
after connecting to an automated (or given to a human) attendent.  For
store-and-forward telephone addressed messaging application, the ability to
use an automated attendent to route is not possible.   The sub-address can
identify the messaging recipient in a corporation by an extension number
behind a single main number.  This is a critical requirement where direct
inward dial numbers are not assigned to all employees reachable behind the
main number.  Similarly, in residential usage, it is common to assign
sub-mailboxes for each resident of a given household.  

Greg V.