It appears that they take payments in as deposits and then disburse the money when another user requests a withdrawal. This requires either a bank charter or a designation as a money transfer agency. Without one of those, they are running an unlicensed bank. You cannot hold the money as an intermediary in the US without satisfying one of those requirements. I don't see anything on the site about either one of them, but knowing at least a little about the capital requirements needed to get one or both of those I would doubt that they have them. Please correct me if I am wrong, I think mobile payments is an idea who's time is past due but its very difficult to pull off in the US.