Four churches in the northern Mexican city of Monterey are using equipment made by Israeli telecoms equipment firm Netline Communications Technologies to block calls during services.
The Tel Aviv-based company was set up in 1998 by former military and defense industry specialists to develop a hand phone jamming system, primarily for the security industry.
Mr. Bulmaro Carranza, a caretaker at the city's Baroque-style Sacred Heart church, was quoted as saying: 'Before we had the system, it was very uncomfortable hearing calls coming in during the celebration of mass. 'Now, it's 95 per cent quiet.'
The signal-jamming equipment is packed into two wall-mounted boxes the size of small hi-fi speakers, with one next to the altar and the other at the church entrance.
Switched on just before the start of every service, the system causes a 'no signal' message to be displayed on worshippers' phones, but causes them no lasting damage.
"We believe that we were the first church in Mexico to use this technology," Mr. Carranza said.
"Now, we are getting calls from all over the country to see how it can be installed in other locations," he added.
Some Mexican churches are using state-of-the-art technology developed by Israeli electronic warfare experts to silence phones that ring during mass.