New Delhi: Industry body COAI has said mobile tariffs may go up soon as telecom operators are expected to pass on to customers the burden of spectrum cost they will incur in the upcoming auction. The auction of airwaves is likely to be conducted in February next year. “Definitely there will be an upward pressure on tariffs as the debt burden of telecom players will increase post auctions, they have to pass on the cost to customers,” COAI Director General Rajan S Mathews told PTI. He said operators have to pay around Rs 40,000 crore for the spectrum even if the airwaves would be sold at reserve price in 900MHz and 1800 MHz bands. Telecom sector regulator TRAI had suggested a 10 per cent higher base price for the next round of spectrum auction in the 1800 Mhz band.