Ekiga doesn't pick up the other end of the call for me when I tried it a few weeks ago (the person is there but no sound output from their side of the call). I actually used Ekiga extensively for a while (I even wrote a partial patch for GCC 4.4 compatibility, this was ~early 2008) and could eventually get it to work most of the time, but it frequently had problems; it would crash, drop sound, leave the device busy from the last call, etc. Lots of problems with it. Went back to Skype.
I tried Wengo (now QuteCom) and couldn't get it to pick up the sound device or something like that. Maybe another PA bug, but PA has been a default feature of Linux desktops for 3-4 years or more by now. I don't remember the exact issue I had with it.
Pidgin isn't made for SIP/VoIP applications but I still haven't ever been able to get the gstreamer connector to respond correctly. The only IM client with which I've had success using video chat is Empathy, but it had a few issues too with closing devices/picking up subsequent calls.
Maybe it's just because I use Arch, but Skype is the only mostly-reliable video conferencing/SIP-like app on Linux that has actually been usable for me.