[OpenSIPS-Users] Presence Aggregation Idea

Damien Sandras dsandras at seconix.com
Sat Nov 5 13:29:46 CET 2011

Dear all,

Presence aggregation is a difficult item in the SIP world.

However, I thought about something and I ignore if it is easily feasible 
or interesting or if it breaks some rules.

Most endpoints (if not all) do not support multiple presence statuses. 
And the SIP RFC's make it difficult to choose which presence to display 
or event to determine which one is really accurate.

Having multiple presence statuses occur when the same extension is 
registered from different devices, and when all of them publish 
conflicting presence states.

OpenSIPS decides to order them chronologically (top down). Ekiga is 
parsing the document and choosing the most recent one (based on a 
timestamp if any). But others are doing things differently.

Would it be a good idea to use the 'q' parameter to determine the 
various resources priorities and have a new setting in the configuration 
to choose to only notify the state with the highest priority ?

That way, if you have a softphone and a desk phone, if you set your 
deskphone to "Busy", but put your softphone as "available" and the 
softphone has the highest priority, people know you are available. Most 
people would think that "busy" would win, but it can simply mean that I 
am reachable but do not want to be reachable through my desk phone. That 
is different than with Jabber, but telephony is different anyway.

Well, to summarize, having a "winning" presence device would solve many 
Damien Sandras

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