[SR-Users] checking if calls are still active

[marius zbihlei]

On 11/01/2010 05:24 PM, Vic Jolin wrote:
> That's interesting, can you tell me more about that draft?
>
Hello

I have attached the draft.
There are 2 setups for using end-to-end OPTIONS ping

1. In Dialog... if one of the endpoints is a B2BUA, it can send at 
specific interval in-dialog OPTIONS ping (OPTIONS request, increasing 
cseq) to the other endpoint. Most well-behaved UAS will respond with a 
481 if the dialog not longer exists as per 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.
"
Other error conditions are on a  408 , 404 etc (as any in-dialog request 
is not guaranteed to succeed).

This is already used some production environments.

2. Out of dialog. A proxy keeps sending OPTIONS request (no dialog 
involved here) to one of the UA as long as one of these 2 conditions exist:
a. the dialog has not ended via a method specific mean (BYE for INVITE etc)
b. a 408 (or other error codes) was received when generating a BYE.

These where the big two points of the draft.

Marius
> On Mon, Nov 1, 2010 at 11:18 PM, marius zbihlei 
> <marius.zbihlei at 1and1.ro <mailto:marius.zbihlei at 1and1.ro>> wrote:
>
>     On 11/01/2010 05:13 PM, Vic Jolin wrote:
>
>         Hi,
>
>         Just want to ask what is the best way to check if calls are
>         still active especially when we are not handling media?
>
>         Thanks
>
>     Hello
>
>     There is SST (Sip Session Timers RFC 4028), which is implemented
>     in the SST module, but at least 1 UA must know the extension. Also
>     I have been working on a IETF draft  to use end-to-end OPTIONS
>     ping to determine the operational status of a UA.(it works well
>     with B2BUA, relatively well with stateful proxies). If you are
>     interested I can talk more about the draft and how I propose using
>     OPTIONS requests for this.(no changes on UAs are necessary)
>
>     Marius.
>
>
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