CAMP FOSTER, Okinawa — U.S. military families in Japan are being advised to turn off baby monitors they brought with them or ordered via mail from the States because they use frequencies that can disrupt radio and cell phone traffic.

It’s a problem that pops up every year during the summer when about a third of military families based in Japan are replaced by newcomers unfamiliar with the country.

The monitors, which broadcast in the 900 megahertz range, can break into frequencies reserved in Japan for cellular phones, along with emergency, taxi and trucking communications, according to Japan’s Internal Affairs and Communications Ministry.

Recent interference incidents have been reported on Okinawa, where about half the U.S. military personnel in Japan are based, and Tokyo, Kanagawa, Yamaguchi and Nagasaki prefectures, the ministry reported.

The problem was so bad last year that military officials on Okinawa went door-to-door in base housing to trace the complaints and make sure base exchanges did not sell the baby monitors, cordless phones and walkie-talkies that operated on the 900 mhz frequency.

The most popular baby monitors sold in the states — Graco, Evenflo and Fisher-Price — all operate on that frequency.

The Army and Air Force Exchange Service’s online store discontinued shipments of such items to addresses in Japan and offers compliant alternatives in its exchanges, AAFES Pacific Region spokesman Jeffrey Craven said Tuesday.

“We don’t sell any noncompliant monitors or telephones in our Japan or Okinawa exchanges,” he said.

U.S. military personnel are advised about the noncompliant devices during newcomer briefings when they report for duty in Japan.

Hiroshi Hentona, chief of the Monitoring and Investigation Team of the ministry’s Okinawa office, said a survey conducted last year showed 33 instances of unauthorized frequency use from housing on bases and some off-base homes rented by Americans.

Stars and Stripes reporter Chiyomi Sumida contributed to this report.

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