TOKYO - A Chinese man was referred to prosecutors Monday for allegedly disrupting a major mobile carrier's services in Tokyo's Ginza shopping district with a rogue cell tower device, with police investigating possible links to a phishing scheme using illegal radio signals.
Yu Hai, 31, an unemployed resident of Tokyo's Kita Ward, was arrested Saturday allegedly in the act of operating a base station without a license, using the device from a car parked on a Ginza street to emit radio signals to interfere with NTT Docomo's services, Tokyo police said. The alleged offense falls under Japan's Radio Law.
Police believe he used an IMSI catcher, a device that collects mobile phones' identifying numbers. They suspect it emitted strong radio signals to force nearby handsets onto an older 2G network before sending them text messages.
Yu has denied the allegations, police said.
Foreign tourists and others at tourist sites across Tokyo began receiving suspicious text messages in Chinese containing web links around January last year.
Police suspect the messages are part of a phishing scheme using illegal radio signals and are investigating a possible connection to Yu.
By October this year, 18 Chinese nationals visiting or studying in Japan had contacted police about problems including unauthorized credit card use after accessing the websites linked in the messages, police said. The reported losses totaled about 4 million yen ($25,300).
Police had been investigating the suspect after observing him traveling through busy shopping and entertainment districts in a car allegedly carrying the equipment.
Japan's communications ministry raised the issue with Tokyo police in January last year. Four months later, it warned the public about suspicious text messages, saying fake base stations were interfering with mobile phone services.
IT journalist Yo Mikami said similar text messages have been reported across Japan, mainly in busy shopping and entertainment districts, suggesting Chinese tourists are being targeted.
He advised people to leave the area if their phone service becomes unstable and avoid opening unfamiliar messages, as fake websites can be hard to identify.
