I don't even get a place to chose.. what is your XML config for this??? 

I saw this in searching for a solution...Set Jabber to "Join in Webex" by default for meetings - Cisco Community but I can't even get ours to work.. XML config old. so likely missing things.

So there is no XML template for 12.x?

still did not resolve issues.

We are on newest Firmware for 8821 / Newest firmware for Meraki,.. Still the phones unregister / drop calls. Very frustrating.Anyone have any further insight?