Why not Empathy? I've been using that for SIP for a long time, and it is really nice. I don't even think I'm using SIP that much even, maybe it's XMPP calls from Google mostly - it just works, I don't have to care about it.
You need to install telepathy-sofiasip to get it, -- but it works, even on my phone (Nokia N9). :-)
I honestly think Telepathy is the best way to do this now. And the different clients that use it (e.g. Empathy) is better to use than to use Ekiga.