I'm and electrical engineer. I followed the installation instructions carefully using only the included equipment. And I was careful to get adequate separation between the unit and the external antenna. Even the diagnostics on the unit itself indicate that it should be a good installation. But the unit only works off and on with the result that calls fade in and out - even if you aren't moving around the house. It happens if you are sitting right next to the unit. The call quality ends up not being improved.I called customer service while trying to debug it and they told me that that you can't tell anything from the flashing lights on the front of the unit. That flashing or not flashing was all normal. From this I concluded that all of their units have problems and only work intermittently.I may have a faulty unit, but I just wouldn't recommend this item. It is a lot of money and doesn't very well.