Re: [Gen-art] Gen-ART LC review of draft-hanes-dispatch-fax-capability-06.txt

[Brian E Carpenter <[e-mail]>]

On 05/12/2012 14:12, Kevin Fleming wrote:
> I suppose it could choose to unregister and re-register in some other way
> in order to achieve its goals of receiving FAX calls, if it was configured
> with enough network information to do so.
> 
> Now that I think about it some more, is a registrar even allowed to return
> a Contact header that differs from the one the UA supplied in its REGISTER
> request? I suspect this is *not* allowed, and so if the registrar supports
> Caller-Pref but the specific tag(s) in question fail some sort of
> validation process, its only recourse would be to fail the REGISTER request
> with a suitable error response.

If that's the standard behaviour, it would of course answer my question.

   Brian

> 
> 
> On Wed, Dec 5, 2012 at 6:35 AM, Brian E Carpenter <
> [e-mail]> wrote:
> 
>> On 05/12/2012 11:01, Kevin Fleming wrote:
>>> The language in RFC 3840 doesn't appear to contemplate the situation
>> you've
>>> proposed. In its world, registrars can either support prefs (and will
>>> accept "Require: pref") or they don't, and they don't have knowledge of
>>> which feature tags are registered with IANA and which are not. Of course,
>>> they *coud* attempt to validate the tags expressed by the UA, but I don't
>>> see an explicit way for the registrar to indicate that the UA included
>>> disallowed tags in its request.
>> Understood, but in that case I don't see what good the confirmation
>> of the tag from the registrar to the UA achieves - the UA is not going
>> to be able to do anything with it (except maybe log whether it was
>> received).
>>
>>     Brian
>>
>