we all have read a few posts about how people say the droid dials on its own. usually the culprit seems to be a cheapO charger fro m ebay. but just in case you are worried that it might happen if figured out a way for it to not happen.
you need google voice and the GV app.
just set GV app to ask you if you want to make your call with GV or with carrier.
this way it will never dial on its own unless you select a method.
you can set this up in GV app settings.
it might be a pain in the butt for some but it might not for others.