Re: [Sip] 199: Staus and open issues after Dublin - support indicator

[Paul Kyzivat <pkyzivat at cisco.com>]

Christer Holmberg wrote:
> Hi Brett,
>
> > > > If UAC does not support 199, sending it might cause more harm than
> good.
> > > A UAC should discard what it doesn't support.
> > RFC 3261 section 8.1.3.2: "A UAC MUST treat any provisional response
> different than 100 that it does not recognize as 183 (Session
> Progress)."
> > The above requirement adds complication for devices (not supporting
> 199) only maintaining a limited number of early dialogs or using latest
> 1xx to recognize most likely active early dialog.
> > The 199 could trigger them to forgot or not prefer a useful early
> dialog for the one associated with 199.
>
> Wouldn't that mean that, if the UAC does not insert the indicator,
> proxies are not allowed to insert it either? Because, if they do, and
> receive 199 I guess they will simply forward the 199 towards the UAC,
> and you end up in the same situation. An intermediate B2BUA could of
> course terminate the 199, and not forward it towards a UAC not
> supporting it, but I don't think we want to define such behavior for
> normal proxies.

If we postulate such an indicator, then why would a proxy *want* to 
insert it? I agree it would be a bad thing.

	Paul
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