Since I use this cell phone jammer and learned its' little nuances it has blocked all numbers required. I had a political party from the DC area that called me constantly even though we had asked them not to. Any time I would block one number from them they would use another. It appears they had an unlimited resource of numbers from a particular area code. Since I had no relatives from there I blocked that area code and it has been quite peaceful. Oh, they still try to call as I can look at a missed call list on my phone system. I smile every time I see they've tried to reach me and it has been blissfully quiet. By the press of a button a number can be blocked. Love it!!