Investigators suspect that the entire operation was handled from Cambodia, with the help of a SIM box installed illegally in the country. During the probe, officers said, it was found that the fraudsters used a SIM box to initiate calls. The location of the SIM box, however, is yet to be traced. It can generate thousands of calls a day by constantly rotating multiple SIM cards,” the officer added. The accused allegedly used SIM boxes recovered from Delhi, Mumbai and Mohali.