[asterisk-users] get SIP extension status without calling it

Vieri rentorbuy at yahoo.com
Sun Dec 2 16:49:54 CST 2007


--- Raj Jain <rj2807 at gmail.com> wrote:

> In theory, UAs that respond to OPTIONS and INVITE
> differently are "broken".
> Below is a quote from section 11.2 of RFC 3261.
> 
>    The response to an OPTIONS is constructed using
> the standard rules
>    for a SIP response as discussed in Section 8.2.6.
>  The response code
>    chosen MUST be the same that would have been
> chosen had the request
>    been an INVITE.  That is, a 200 (OK) would be
> returned if the UAS is
>    ready to accept a call, a 486 (Busy Here) would
> be returned if the
>    UAS is busy, etc.  This allows an OPTIONS request
> to be used to
>    determine the basic state of a UAS, which can be
> an indication of
>    whether the UAS will accept an INVITE request.
> 
> In practice, as you're seeing it yourself most UA
> implementations treat
> OPTIONS as a health-check and capability discovery
> mechanism. 

Thank you for explaining Raj.

It sounds depressing though.
Looks like all major UAs have the same behavior and
don't comply to section 11.2 of RFC 3261 (tested
Grandstream, SJphone and X-Lite).

If someone knows of a UA that actually does comply
please let me know.

Thanks.



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