IMSI vs IMEI: What Your Phone Broadcasts and Who Can Read It

In April 2026, BleepingComputer reported that Canadian authorities arrested three men for operating an “SMS blaster,” a device that pretends to be a cell tower to send phishing texts to nearby phones.

It’s a close cousin of the IMSI catcher, the fake-tower device used for surveillance. Both work by tricking phones into connecting to the strongest signal and sharing information before anything is authenticated.

One of the main things a fake tower can collect this way is your IMSI, the identifier tied to your SIM, but it’s far from the only thing your phone gives away.

Your phone has several radios that connect to different kinds of signals and share different information.

The Wi-Fi and Bluetooth radios share hardware addresses, which modern phones randomize or rotate to reduce tracking.