"Some instances of busting of illegal phone exchanges by the Anti Terrorism Squads have come to notice," Minister of State for Home Hansraj Ahir said in a written reply.
Ahir said ILD calls from foreign countries are routed through Voice over Internet Protocol (VoIP) bypassing the International Long Distance Gateways.
"These incoming VoIP calls are converted into voice calls which are further routed to the destination through local telecom network," he said.