Busy signal in Belize

[belizean]

I bought a magicjack in the U.S., registered it and it worked fine. I sent it to Belize, in Central America, along with the laptop, but it doesn't work in Belize. All they get is busy signals when trying to place a call to the U.S. I understand that maybe the country is blocking certain voips. Anyway to get around this block, by using a proxy? If so, please explain as I'm a newbie.