Appreciate the honesty and quick actions on behalf of matrix sim cards. I had bought their international sim card for US and after 4 days of using it perfectly, the phone started acting in a distorted way. I had to finally call the customer support team for an understanding of the issue. I was made to understand that the issue was with certain AT&T numbers from Matrix. I was asked to wait until day end for a response in terms how long would they take to resolve it. I actually did get an email at day end stating things would be resolved by next day noon. Honestly a few hours without the phone ringing sure did feel good. Having said that, my experience with matrix was good. Recommended!