One thing to keep in mind with any SIM that uses a callback system. The call must go from where you are, back to the switch and then to wherever the called party is located. This means that a conversation between two people must make multiple international hops. I knew someone who used a SIM like this to make local calls in Japan and found the delay was so bad that his wife refused to talk on the phone. Bottom line is that if you plan to use the SIM for local calling you should find one that does not have to make intercontinental hops.