NEW DELHI: Acting on a tip-off given by a Military Intelligence Unit of J&K, the Andhra Pradesh Police on Wednesday unearthed three illegal VOIP (Voice Over Internet Protocol) exchanges in Vijayawada area and arrested seven people.Three "sim boxes", more than 230 sim cards, laptops, desktop computers and other peripherals have been seized. More arrests are likely.According to police, the facilities were being exploited by intelligence operatives from Pakistan for making calls to security personnel in J&K to acquire sensitive information from them by posing as senior army officials."Earlier this month, an intelligence pertaining to suspicious illegal VoIP exchanges being run in Gunadala area of Vijayawada was shared with us. It was learnt that these exchanges enabled callers from other countries call an Indian numbers by hiding their identity and showing some Indian numbers to their receivers instead," said a senior cop.According to cops, the calls were made using VoIP technology through the internet and converted into regular telecom calls (using a modem like device called sim box and illegally procured SIM cards). They were then routed to the desired Indian number in the guise of a legitimate telecom call from another Indian number.This potent modus operandi was adapted to make the security personnel believe that the caller is an Indian.The inputs were further developed by Andhra Pradesh Police with assistance from local TERM Cells.The state police could soon detect hundreds of illegal SIM cards being used, locate the illegal facilities and identify the individuals involved.They further could identify and locate the kingpin who was running these exchanges along with others established even outside the state. Suitable leads were obtained and multiple simultaneous raids were planned in Vijayawada."It is belived that these facilities were also used for monetary fraudulent activities. Apart from being a security concern such exchanges cause huge financial loss to the exchequer by providing an illegal alternative to other recognised means of making international calls to India," the officer added.Earlier this year, illegal VoIP exchanges were unearthed in UP, MP, Telangana, Maharashtra and Odisha. These exchanges were being exploited by foreign spy agencies to target security personnel apart from being used by various fraudsters.