Had zero effect. My windows must already allow enough signal through for this to not make a difference. Bought it for the back of my place because I get full bars right outside on the patio, and almost none inside (I live in a concrete apartment). If I put the phone in the same place I had this, I get good reception, but this didn't extend my signal any, or act as a repeater. Didn't seem to help in the car either, but I don't really need it there.