Jabber uses an enhanced license and can borrow from upper tier as any other device. So since you have 289 enhanced licenses you can have that many jabber clients plus all of your upper tier licenses that are available. If you start adding in a user phone device with the jabber client then you bump up to enhanced plus.
So the count would be:
289 Enhanced licenses + 1048 CUWL Standard (97 already used) + 142 CUWL Pro = 1479
If I'm wrong someone correct me, licensing has always been a pain for me and am trying to get it right. Keep in mind as I said, the moment you associate another device to a user with a Jabber client you start to burn an Enhanced Plus, if you add three or more device you go up yet another tier. If the goal is to just have a jabber client for IM purposes, enhanced will work fine but just keep in mind all of your other devices you may have in public/anon mode.
