U.S. Secret Service Dismantles 300 SIM Servers and 100,000 SIM Cards Disabling Cell Phone Towers
The U.S. Secret Service has dismantled a massive, sophisticated network of electronic devices in the New York tristate area, thwarting what it described as an "imminent threat" to senior U.S. government officials and the agency's protective operations.
Crude but effective. Just guessing, but I'm figuring someone found it odd that one source was paying monthly for 100k lines. Or one address was getting a whole bunch of mail.
Probably all prepaid.