Telecom Regulatory Authority of India, TRAI, Chairman, Ram Sewak Sharma has said that increase in call drops in the past five-six months cannot be attributed to lack of spectrum. In an exclusive interview to All India Radio, he said mobile operators will have to invest in expanding infrastructure to overcome the problem of call drops.<br/><br/>On digital India initiative, Mr. Sharma said that TRAI is convinced about the efficacy of the programme, especially for rural India. The full text of the interview with the TRAI Chairman can be heard in our Countrywide programme tonight from 9.30 p.m. on FM Gold channel and additional frequencies.