Skype is all free except for calling. No, I don't mean facecams and microphone calling. I mean like ACTUALLY calling people from their cell phones or phones. You do get one free phone call, but then you have to pay for it if you want to call people from their phones.
It won't cost you anything. You can download it from Skype website and use it for free. It's the best messenger program for online chats, video and voice chats. Besides, you can use it to download files from your friends (they should be using it too then). If you want to use it to make a call to your friend's phone - then it is charged, I guess..