After several years of telemarketers calling we finally decided to invest in a call blocking device. We selected this cell phone jammer. We have had it for several weeks. We had an initial problem with calls going to our Verizon voice mail vs the voice mail on our home phone unit. A call the tech services at CPR recommended we reduce the number of rings before the voice mail kicks in. We did that and it solved the problem. The unit has blocked untold numbers of telemarketers and our house is not much more peaceful. This device is easy to use, install and is works.