Subject: [Sipping] Kill Overlap Dialling

From: "Christian Stredicke" <[email-masked]>
Date: Tue, 26 Aug 2003 11:06:55 +0530

Hi All,

the feedback which I received so far on overlap dialling was pretty
clear: There will be no overlap dialling support for SIP.

Arguments:

A. ENUM does not support overlap dialling. There are security concerns
on who will own the nodes of incomplete numbers and it was also reported
that the overhead for the node lookup is too much.

B. Countries with fixed-length numbers (like USA) can have a dial plan
on the phone. Other countries always need to press the dial button
except for cases where extension numbers are dialled. People calling
from the US have to press a dial key (or #) after dialling a non-US
number. That is accepted by the customers.

C. The lack of support of 484 responses on PSTN gateways makes overlap
dialling unusable anyway. A SIP extension would be necessary, but does
not exist at this time and the probability that we reach consensus on
such an extension in time is minimal. 

D. "Grandma" is not in the customer focus any more. "Grandchildren" are
used to cell phones and press the dial button after making up their
minds on which person to call.

E. Phones without display will not be sold in large numbers any more. If
vendors should decide to make SIP phones without display, they must
include a dial button (timeout of 5 seconds to start dialling is not
feasible as this makes printed telephone book lookup impossible).

Am I right? I this is so, we would like to stop efforts on implementing
this in out endpoints.

Best,

Christian

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---

From: Cary FitzGerald <[email-masked]>
Date: Tue, 26 Aug 2003 11:37:07 -0700

It would be fine for individual products to make a decision that they 
support only en bloc addressing, but it would be a mistake to 
eliminate the possibility for any SIP-based product to support 
overlap dialing.  As you point out, providers of the cellular network 
have made this decision on behalf of their customers.  You could make 
the decision to support only en bloc for your product without 
affecting the SIP standard.

To your point (C), are the procedures outlined in 
<http://www.ietf.org/internet-drafts/draft-kotar-sipping-dss1-sip-iw-
01.txt> and 
<http://www.ietf.org/internet-drafts/draft-elwell-sipping-qsig2sip-03
.txt> unworkable?

Cary.

--On Tuesday, August 26, 2003 11:06 AM +0530 Christian Stredicke 
<[email-masked]> wrote:

> A. ENUM does not support overlap dialling. There are security
> concerns on who will own the nodes of incomplete numbers and it was
> also reported that the overhead for the node lookup is too much.
>
> B. Countries with fixed-length numbers (like USA) can have a dial
> plan on the phone. Other countries always need to press the dial
> button except for cases where extension numbers are dialled. People
> calling from the US have to press a dial key (or #) after dialling
> a non-US number. That is accepted by the customers.
>
> C. The lack of support of 484 responses on PSTN gateways makes
> overlap dialling unusable anyway. A SIP extension would be
> necessary, but does not exist at this time and the probability that
> we reach consensus on such an extension in time is minimal.
>
> D. "Grandma" is not in the customer focus any more. "Grandchildren"
> are used to cell phones and press the dial button after making up
> their minds on which person to call.
>
> E. Phones without display will not be sold in large numbers any
> more. If vendors should decide to make SIP phones without display,
> they must include a dial button (timeout of 5 seconds to start
> dialling is not feasible as this makes printed telephone book
> lookup impossible).
>
>
> Am I right? I this is so, we would like to stop efforts on
> implementing this in out endpoints.
>
> Best,
>
>
> Christian
>
>