I've used Pidgin, but it hasn't worked 100%, so maybe you know about something better...
I used to use
pidgin-sipe in Pidgin. The same plugin apparently works through empathy too.
I say "used to" because I'm not longer in an environment where I need it, not because I found anything better. As far as I know, it's the only plugin to tackle the problem.
In short, I think you're left trying get your problems fixed (report a bug), rather than jumping boat to another project... Which is probably healthier for both of you.
As it was said, you can use either
Empathy (installed by default on UBuntu) or
Pidgin (available in the Software Centre), as long as you install the following plug-in which works for both:
There is a detailed explanation of the steps on this forum thread: http://ubuntuforums.org/showthread.php?t=1291311
Look for Huygens' (myself) posts.