O2 VoLTE: locating any customer with a phone call

“Any O2 customer can be trivially located by an attacker with even a basic understanding of mobile networking.”

O2 UK’s network sent callers the recipient’s IMSI, IMEI, and cell ID on every 4G call. That was enough to locate customers, even abroad. O2 ignored emails to its CEO for two months. It said the leak was fixed two days after the post went public.