If you have a card on your door, we are not selling anything.  We were hired by the local cellular provider to locate a signal.  You have a cell booster or a device that has failed and is sending out a signal that can be seen from miles away and has led us to your door.   It is not your fault, they just break after some time and can cause issues with internet and sometimes E911 services.  Give us a call and we can discuss further.