I have been averaging at least four unwanted calls each day. Telling these people that your number is on the National Do Not Call List does not stop them. I did not want to change my telephone number and pay to have it unlisted. I read about the cell phone jammer online, and I decided to buy it. Set up took about three minutes. I then tested it out by using my cell phone to call myself. I blocked my cell number. The jamming device worked. My land line did not even ring. In fact, I have not received a single unwanted call since I hooked it up to my phone line. If you are fed up with telephone solicitors, buy the device.