Suzanne Trent: "Can't we set individual trust codes in the software?"
Allen Walker: "The FBI's anti-tracking system here targets the eavesdropping capabilities of many underground forces in the United States, completely blocking all signals with great intensity, so it's impossible to set up trust codes. As for the ones in our country, they have long been regulated and are not allowed to be used. So even if I gave you the software, it would be removed by antivirus software once installed on your phone and become useless."
In other words, using the high-tech software provided by Allen in the United States to block the signals tracking her was not the most appropriate way.
So the only option left was to temporarily change the SIM card and phone.