They cannot access your money, they need to make you send them an SMS with costs added (like the ones your phone wanrs you about, only that not every phone warns if there is a SMS to a pay-number).and how can they reach my money without access to my account? I have it so I pay a set amount of money to my phone company only, so they can't take any money off my phone. (And even then the phone usually alarms if you are about to send an sms that costs money).
