You can not download Skype from BB app stor to a BB . So it well still cost you . Free chat is available with whatsapp. The problem is BB are out dated . The onley thing thy still have going for them and is why u see them in the DR and laten American is for the free pin text option.
Google Voice, as far as I know, is only free to call phones in the US and Canada and it must be set up "in the US or Canada" not the DR for that to work. You can use Google Voice to call DR phones, but you need to pay for that. There is no free way to call DR phones that I know about.