Rayhunter works by intercepting, storing, and analyzing the control traffic (but not user traffic, such as web requests) between the mobile hotspot Rayhunter runs on and the cell tower to which it’s connected. Rayhunter analyzes the traffic in real-time and looks for suspicious events, which could include unusual requests like the base station (cell tower) trying to downgrade your connection to 2G which is vulnerable to further attacks, or the base station requesting your IMSI under suspicious circumstances.

All good advice except for the tip to carry this with you in your wallet because I feel the border thugs would use that as a reason to mess with you. Plus it's missing the best tip: don't travel here any more because it's not safe.