I top up my Jamaican phone from home with ezetop as well. I put $5.00 US (your credit card will be charged $5.65) every 90 days to keep my sim active. Sometimes I will have to add 100J when I get to Negril to make a call but if you top up every 90 days all your credit will still be there. The last 2 trips I topped up the day before we left home and my phone worked on arrival. Incidentally almost every time I top up my credit card company (Capital One) contacts me to see if I authorized the charge.