If your phone has the GSM 1900 frequency band it will work. If it is unlocked you can buy a prepaid BTL sim card in Belize, that is the cheapest way to go as long as you don't mind having a different number.
For outgoing calls, you can use your computer - go online to skype and use the phone function. it costs about 3 cents (US cents) a minute to call a telephone from your computer.
The opinions and views expressed on this board are the subjective opinions of Ambergris Caye Message Board members and not of the Ambergris Caye Message Board its affiliates, or its employees.