MOVIES, concerts and plays need never again be interrupted by the ringing of
a mobile phone, as an Israeli company has found a way to block cellphone
signals.
Netline Technologies will soon start selling 鈥淐-Guard鈥�, a short-range
wall-mounted device that prevents mobiles taking or making calls. It鈥檚 effective
against all digital mobile formats.
C-Guard broadcasts low-power signals in a part of the mobile phone spectrum
reserved for control signals between a base station and a phone, which ensure
that only calls intended for that phone reach it. But C-Guard scuppers this
鈥渉andshake鈥� operation, so any phone within the area covered by the C-Guard
signal will display a 鈥渘o signal鈥� message鈥攁s if it were out of range of
the mobile network.
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Netline says C-Guard can be used for spaces as small as offices or as large
as convention centres and concert halls. The system can also be programmed so
that some phone numbers still work. 鈥淵ou can create live spots within the dead
zones,鈥� says a spokesman. This would be useful in hospitals where the phones can
interfere with medical equipment but where doctors may need to be reached by
mobile.
Although the device is not yet certified for use on aircraft, where some
insist on using mobiles despite a ban, Netline says C-Guard鈥檚 very low power
signals will not interfere with aircraft control systems.