Subject: RE: [Ecrit] Issue 30: Requirements regarding Emergency Identifiers

From: "Stark, Barbara" <[email-masked]>
Date: Thu, 19 Jan 2006 15:03:21 -0600

I see that my suggestion (of VSPs sending an OPTION message when they detect an emergency call digit string, but which the SIP endpoint did not detect as an emergency call) isn't popular, so I retract it as a suggestion. Please forget I ever mentioned it. Since the option to do this exists, and nothing in the architecture precludes it, it's really irrelevant as to whether or not ecrit chooses to acknowledge existence of this scenario.

However, on my comment about home and local numbering plans, I think I'll stand my ground, and state more concisely what I'd like to see.

1. ecrit should not be attempting to require recognition of any specific dialing string. The ecrit architecture depends on UAs being able to recognize emergency digit strings and translate them into an emergency SIP URI. It also depends on these strings being configurable (so device dialing plans are not tied to the area where they were bought). And that's as far as it needs to go. Nothing in the ecrit architecture depends on the recognition of a particular string of digits. Given that the architecture is completely independent of specific string values, the only entities that have the authority to tell me what emergency strings I MUST recognize, are the various governmental bodies that have jurisdiction over the services I offer. ecrit is not such an entity and does not need to try to take on the role of the FCC. 

2. If a mechanism exists to send local emergency numbers to a device, devices  must be configurable as to whether or not they make use of this mechanism.

I believe that the results of using this mechanism could be undesirable, could cause confusion of my customers, and could either not work properly or interfere with my customers' local dialing plan. Again, all I'm asking is that use of this mechanism (if it exists) be configurable, so I can turn it off or default it off in devices I provide to my customers.

By the way, while you may not have dialed 00, many people do make use of it. It is a valid convention in US dialing plans, and it lands you at a real, live international operator. Personally, I've never dialed 911, but I'm not willing to give it up as part of my dialing plan. Again, ecrit has no authority to interfere with or specify digit dialing plans.
Barbara 

Barbara Stark
BellSouth Science & Technology

-----Original Message-----
From:	Henning Schulzrinne [mailto:[email-masked]]
Sent:	Thu 1/19/2006 10:00 AM
To:	Stark, Barbara
Cc:	[email-masked]
Subject:	Re: [Ecrit] Issue 30: Requirements regarding Emergency Identifiers
The problem is default configuration. I presume we'd want systems to  
be configured by default to be secure and privacy-safe, i.e., refuse  
the request without explicit user (GUI) approval. GUI approval isn't  
nearly as helpful for emergency calls. Thus, in practice, either all  
systems would be privacy-unsafe out of the box or this mechanism  
would fail in an emergency. I don't think forcing users to give up  
location privacy for all calls (or manually twiddling configuration  
options before each call) just so that emergency calls work is an  
acceptable design.

I think labeling emergency calls is a much better option and follows  
the general SIP design principle of declaring, rather than inferring,  
intent.

I believe the dial-plan issues are solvable for the vast majority of  
cases, although I agree that we need to specify behavior sufficiently  
well to achieve desirable outcomes. Your mechanism fails to protect  
the user's privacy; the labeling mechanism fails under rather obscure  
circumstances for calls that few people care about. (I can't remember  
ever having called the international operator...)

On Jan 19, 2006, at 9:50 AM, Stark, Barbara wrote:

> Assuming that the OPTIONS mechanism (described in Section 8.2.2 of  
> draft-ietf-sip-location-conveyance-01.txt) exists, there's really  
> nothing you can do to prevent any party you call from sending this  
> request. The question is, what does your SIP endpoint do with the  
> request when it gets it? If your SIP endpoint is configured to  
> always return a 488 reply, then your privacy remains uncompromised,  
> and (going back to the example of what a server that recognizes an  
> emergency call might do) your emergency call gets routed according  
> to your emergency location of record. On the other hand, some  
> people may not really care if their location is known when they  
> call somebody, and may have their SIP endpoint respond to such a  
> query with an OK and the location info. Since this is all under the  
> control of the person who manages the SIP endpoint, I'm not sure I  
> see the privacy issue.
> Barbara
>

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From: Henning Schulzrinne <[email-masked]>
Date: Thu, 19 Jan 2006 16:41:57 -0500

> 1. ecrit should not be attempting to require recognition of any specific 
> dialing string. The ecrit architecture depends on UAs being able to 

No IETF working group can require the implementation of anything (or the 
correct implementation of anything...). At best, we can provide 
mechanisms that people find useful.

> 2. If a mechanism exists to send local emergency numbers to a device, 
> devices  must be configurable as to whether or not they make use of this 
> mechanism.
> 
> I believe that the results of using this mechanism could be undesirable, 
> could cause confusion of my customers, and could either not work 
> properly or interfere with my customers' local dialing plan. Again, all 
> I'm asking is that use of this mechanism (if it exists) be configurable, 
> so I can turn it off or default it off in devices I provide to my customers.

That seems, to me, an implementation issue. For example, DHCP, as a 
classical configuration protocol, is configurable in most cases, in that 
  one can choose to use it or hard-code the IP address.

> 
> By the way, while you may not have dialed 00, many people do make use of 
> it. It is a valid convention in US dialing plans, and it lands you at a 
> real, live international operator. Personally, I've never dialed 911, 
> but I'm not willing to give it up as part of my dialing plan. Again, 
> ecrit has no authority to interfere with or specify digit dialing plans.

We auto-configure dial plans all the time today. This is just another 
configuration option.

Since we're talking about requirements here, maybe we should get back to 
those:

- Emergency calls should be recognizable as such by the user agent.

- Both "home" and "visited" emergency numbers should be available 
automatically (for customers that want this feature).

Can we agree on those?

Henning