Hi, wanted to say that yes ekiga does work on android but it depends on what sip client you are using. For example I have a custom rom that runs android 2.3.3 (gingerbread) and I can't register to ekiga using the built in native client for my rom. When I try to register I get a 606 error. Now if you want to use your ekiga sip, and want it to register then you will have to use a different sip client than the built in one for android gingerbread os. Those android sip clients that allow ekiga to register include sipdroid, csipsimple and linphone. Out of the 3, I having used all of them, would say csipsimple is the best.
Now in terms of video calling in android while using sip, I have never been able to with any of the sip clients like the built in one in gingerbread os, csipsimple, sipdroid, and linphone, I also don't think csipsimple, linphone support video calling and video conferencing. The two things that I do know of that do, do video calling is the new Google talk included for android 2.3.4 (where you can video chat with your friends who are on Google talk) and fring's app which allows video calling but not over sip and only through there network, which is similar to Google talk which if your friends have fring you can video call them (I think they allow up to 4 way video calling). Other than that I don't think there are any other apps for sip on android that does the whole video calling and conference, but most of the sip apps on android in my opinion are solid and great for audio calling, especially since I don't think at least here in the states, video calling through voip/sip has caught on. Which is bad because if there was a large demand for video calling then more developers could make there sip clients do so. If you want more info check: http://ekiga.1756082.n4.nabble.com/Ekiga-net-account-with-Android-2-3-4-native-SIP-client-td3532411.html and http://wiki.ekiga.org/index.php/Which_programs_work_with_Ekiga_%3F
This is info about fring: WWW.fring.com