I'd look at getting a local SIM in the Bahamas
http://www.btcbahamas.com/main_flash.html
Then use callback, perhaps in conjunction with cheap VoIP forwarding. Most of the Betamax brands charge in the range about 4 cents a minute, though one is 0c so with a bit of work you might make free calls, unless the BTC network charge incoming calls (which I can't actually figure out on their website)