Telecom Regulatory Authority of India, TRAI on Thursday slammed telecom operators saying there is no significant improvement in the call drop issue in Mumbai and Delhi.It said, operators are lagging on various fronts in meeting the standards.The regulator said that in Mumbai, no operator is meeting the benchmark while in Delhi three top players Airtel, Vodafone and Aircel are found to be lagging in offering good quality services.As per data shared by TRAI, call drops on network of Idea Cellular, Reliance Communications and Tata Teleservices have improved in Delhi.The regulator had in June and July conducted drive tests in Mumbai and Delhi, which showed unsatisfactory network quality.TRAI than convened a meeting of all telecom operators to improve quality of network.To assess the improvement, TRAI had undertaken repeat drive test in Mumbai and Delhi on September 27th and 28th, 2015 to assess improvements.