Cell phones have become a problem for many churches. I have a friend who puts the number of the local Pizza Hut up on the big screen before service with the words, "If your cell phone rings during the service, you have to buy pizza for everyone in attendance today."

Some churches in Mexico are using state of the art technology developed by electronic warfare experts to silence cell phones that often ring during worship services. Four churches in the northern Mexico city of Monterrey are using equipment developed by defense and military experts to jam mobile phone systems. The signal jamming equipment is packed into two wall-mounted boxes the size of small speakers. One is located beside the altar, the other at the entrance. When switched on before a service, the system causes a "no signal" message to be displayed on the phones.

Bulmaro Carranza, caretaker at one of the churches, says before the system was in place, it was uncomfortable hearing calls coming in during services. He says, "Now ...