I use Phonecontrol.net in Centrafuse, it has the best features by far, but it only works when it feels like it. In CF 2.0 it's replaced with bluesoleil, and that doesn't work with what I have, a BCM94025-something usb dongle with Widcomm drivers.
RRmobile, as I read it seems like it was abandoned unfinished.
As for Freefone, I found it to be the most simple and stable plugin, however, it lacks one of the most important features, like voice transfer. Using it is as dangerous as using the phone itself, since after dialing you have to raise it to your ear, and risk causing an accident