Re: [sipcore] Last Call: <draft-ietf-sipcore-status-unwanted-04.txt> (A SIP Response Code for Unwanted Calls) to Proposed Standard

[Pete Resnick <[e-mail]>]

On 21 Mar 2017, at 12:05, Alan Johnston wrote:

> If you are proposing using a SIP response code  603 and with a header 
> field
> Decline-Type: spam, the problem with this is that in SIP, failure 
> responses
> (non-2xx) are delivered hop-by-hop and not end-to-end.  This means 
> that
> although the first hop (proxy) will get the Decline-Type:spam header 
> field,
> any future hops will not.  Instead, they will just get the 603.
>
> A different response code such as 666 will be conveyed end-to-end, so 
> every
> proxy and the calling UA will get the semantics.

Adam walked me through the last few paragraphs of 3261 section 6. It's 
not clear in that text whether proxies will or won't preserve the 
headers, but if they don't, I expect that's a showstopper for my 
proposal. That's a bummer, because I do think the status code is going 
to cause future heartburn. However, if you SIP folks conclude that the 
header will not get through proxies (and I will take you all at your 
word if you so conclude), and this mechanism does need to survive 
proxies (which I suspect it does), then I think we're stuck with the 
status code.

If so, I will happily return to you all to your discussion of whether 
particular numbers do or do not belong in IETF specifications. :-) (For 
the record, I thought 451 set a poor precedent, but I'm a curmudgeon.)

pr
-- 
Pete Resnick <http://www.qualcomm.com/~presnick/>
Qualcomm Technologies, Inc. - [phone]