I'm just being careful with Skype mostly. I try not to go overboard with making too many calls at once. The time they stole $60 from me, I had spent an hour dialing the same number over and over constantly. I chatted with a rep and explained what I was doing to her and she fixed it and my account came back. But then a day later they shut it down permanently.
One alternative might be Voxox. They don't have unlimited, but their rate for U.S. calls is just 1 or 2 cents per minute. So an entire hour of calls would just cost you 60 cents. That seems reasonable and might even be cheaper than Skype for some people.
I'd read that WhatsApp is going to start offering phone calls soon. Right now they do texting for $1 per year so their rates should be good. And then there's Google Voice which is completely free. And you can dial numbers from Google Hangouts, so if you're looking to conference with friends while prank calling, that could be something. I don't know anyone that does that though. Everyone just uses Skype.
