If you have access to wi-fi, and a Droid phone of some sort, you can get an app called Groove IP that works with your Google Voice # to make and receive calls and texts over data connections (wifi or, at home, 3G too). The app is $5 but there is no monthly charge for it or for Google Voice.
If you need the data connection I agree Digicel is probably the way to go, just thought I'd mention the app option.
