Subject: RE: [SIP] Informing UA after network initated deregistration?

From: Jonathan Rosenberg <[email-masked]>
Date: Mon, 12 Mar 2001 04:13:31 -0500

> -----Original Message-----
> From: Baniel Uri-CUB001 [mailto:[email-masked]]
> Sent: Saturday, March 10, 2001 8:42 AM
> To: 'Igor Slepchin'; 'William Marshall'; [email-masked]
> Subject: RE: [SIP] Informing UA after network initated deregistration?
> 
> 
> Igor
> 
> Network initiated deregistration may happen for various 
> reasons. Ironically I do not see 'registrar crashing' as one 
> of them... (Hot backup etc is just as you say far beyond SIP 
> and shall not concern us in this regard). It could be for 
> instance: temporarily suspension of services for a specific 
> subscriber, because his/her pre paid billing ticket is empty...
> 
> I think it is expected by a subscriber to be notified when 
> the system can not serve him/her. 

Really? I'll have to look for that "you didn't pay your bill" lamp on my old
Radio Shack phone... I think the more common expectation is that when
service is denied for non-payment, you get letters in the mail and phone
calls. Thats a provisioning and billing issue.

In general, I think Igor is right on the money here. The need to know
whether or not a registration is still in place, or whether the
registrar/proxy is down, is an application issue, and how to do it (and
indeed why) depends on the particular requirements. As such, I am against
defining a generic mechanism to notify when a registration is deleted, until
we come to a clear understanding of a specific need that cannot be addressed
better using other means. To date, I don't think I've heard one.

> He/she may be a bit cranky if he/she was expecting a very 
> important call, and only after 20 minutes has realized the 
> phone was out of service.. (These are exactly the things that 
> distinguish between real systems and kids/hackers toys)
> (again just like the cellular analogy).

So, whats out of service? My registrar? The firewall? The router? The
etherswitch? The acess networks? The DNS servers? What if my registrar is
up, but my local outbound proxy is down? So many systems are involved in
allowing a "phone to be in service", that simply defining a notification
from the registrar that alerts when it is about to fail seems useless.

Also, my definition of carrier grade is that "it works reliably all the
time", not that "it often doesn't work, but is kindly enough to tell the
phones about it". 

-Jonathan R.
---
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.cs.columbia.edu/~jdrosen         PHONE: (973) 952-5000
http://www.dynamicsoft.com

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From: Stephen Terrill <[email-masked]>
Date: Mon, 12 Mar 2001 12:04:11 +0100

Hi,

It is worth keeping in mind that in some environments, a very popular subscription method in some countries is "pre-paid".  The subscriber will be informed when the service is to be removed to allow them to increase the avaiable credits.  It would be useful for the terminal to understand that the registration has been terminated in these circumstances.  In this environment, some operators do actually send a message (text) to indicate that service is not available due to lack of credits.

In such an environment, it is useful to be able to inform the UAC that the registration is not valid so the appropriate action can be taken by the user or the terminal.

BR,

..//Steve