A Credit Card collections got my number when my friend used my house as a shipping address?

You see my friend was visiting out of state and used my house as a shipping address when he bought something online. But unfortunately a credit card company called Discover Financials has been relentlessly calling my house asking for my friend non-stop. I know when he used my shipping address he didn't use my phone number at all since he showed me proof. So how would this credit card company get my phone number when I'm not even listed?