The Telecom Dispute Settlement and Appellate Tribunal (TDSAT) today issued notices to the Telecom Regulatory Authority of India (Trai) and mobile operators Bharti Airtel, Vodafone Essar and Idea over recent tariff increases.The TDSAT chairman directed Trai and the three operators to file their replies within a week.The notices were issued on a petition filed by the Telecom Users Group of India, an NGO, challenging the recent price hike by the three service providers and requesting the tribunal to put the tariff hike on hold. It also sought a direction to Trai for looking into the hike.The NGO also requested TDSAT to direct the operators to put on record that they would refund the excess amount to their customers if they lost the case.The operators had raised charges for local calls by 20% and international calls by 20 to 32% in August.The petitioner said the companies were raising tariffs just to earn huge profits. It added that the operators, which virtually control 64% of the market, already earn high profits so there was no urgency to increase tariffs. "It was not just a 20 paisa hike in the tariff. It was virtually a 20% increase and with it the telcos would earn Rs 8,600 crore extra every year," the NGO's cousel Meenakshi Arora said.