Thrissur: The Kerala division of BSNL blocked around 5,000 SIM cards after finding that they were used for running parallel telephone exchanges. Though other service providers also have blocked the SIM cards, the total number is unknown. The cads were collected from Odisha, Assam and West Bengal in bulk.

The service providers were being tricked by these groups through parallel exchanges for quite some time. However, BSNL’s Fraud Management System ramped up the investigation recently as they noticed an increase in the illegal activity since January this year.

They set the following criteria for the investigation:

1. Numbers that make more than normal outgoing calls.

2. Numbers with zero incoming calls.

3. Numbers that have more than 22 hours of outgoing calls.

Hundreds of numbers were discovered from Kozhikode, Eranakulam and Thrissur districts. A parallel exchange was busted at Kadavanthra in 2020.

The IMEI numbers also were blocked when BSNL initially found out the irregularity. However, they masked the IMEI to bypass the block. BSNL has discovered a way to figure them out.