Salam...
It doesn't work?
in our masjid we use another thing...it is a machine wich desables the mobiles network in here it costs 177 us dollar.it can desables 400 m² of the masjid a brother brings it to the masjid as a charity...and it works good
well SAid brotherOur masjid has signs all over, and like mentioned above our Imam has repeatedly asked to have the cell phones turned off. He's even asked for them to NOT be on vibrate because when the cell vibrates everyone close to it can hear it, but it doesn't stop them. One brother during Jumuah had his phone on the ground between his feet while we were standing in the lines, and it rang and rang and rang...and when the caller didn't get an answer, they called back! It rang throughout the entire first rakat!!!
Once we had a visiting shaykh who, after we had just prayed Isha when one person let his phone ring through the recitiation, said to us during the lecture afterward "Your salaat isn't more important than your brothers' salaats... so when your phone rings, reach into your pocket and TURN IT OFF!!!"