TSCHARN, Peter (Peter) wrote:
I have the feeling of recognizing discussions during specifications of
ISDN supplementary services. Here also the point was made to simply
redial up to the proposal to do it automatically. These discussions had
an end when BT during the nineties had to face the fact that in their
network automatically fast redialling fax machines seized significant
carrier resources. Thus an exponentially increasing interval between
automatic redial attempts was introduced. This was not seen as a
convenient solution for voice calls.
The use of techniques such as exponential backoff is easier to introduce
when the implementations are all regulated. In an open environment it is
much like flow control. As with that, while following the rules serves
the "greater good", any single user can gain advantage by violating the
rule. Even if the UAC implements the exponential backoff, the user of
the UAC, having recognized this, can still "cheat" by simply repeatedly
pressing the "redial" button. (Which is what many of us did for many years.)
IMO a redial approach is quit inferior to what could be offered by CC
functionality - for the caller (assumed CC is supported at callee side),
the callee (unnecessary ringing) and carrier (save of resources).
The queued implementation is better for the "greater good". It must
however be mandatory when present or else some callers will find that
repeated dialing can still be advantageous. So returning busy for any
but the selected caller is important. That then breaks any UAC that
implements CC only via repeated dialing. To provide a functional service
the UAC then must implement this CC feature when its offered by the callee.
Because this is self regulating, it seems preferable to an exponential
backoff on a repeat dialing approach.
Thanks,
Paul
Regards
Peter
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf
Of Huelsemann, Martin
Sent: Dienstag, 19. August 2008 09:41
To: [EMAIL PROTECTED]; [EMAIL PROTECTED]
Cc: [email protected]
Subject: Re: [BLISS] thoughts on draft-ietf-bliss-call-completion-
deployment
But if I was given a choice of a phone the only did repeated dialing,
vs one that only provided the feature if the callee supports it, I
would choose the former.
I don't think there will be a 'versus'. CC will be an additional
enhancement to the basic 'repeated dialing' feature. So it is also in my
ISDN terminal. But I use the repeat dialing only when there is no
indication that CC is possible, because my call will be queued anyway.
BR, Martin
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