Mr Takorn acknowledged that operators needed to boost their subscriber base in order to optimise their investment in networks, resulting in network traffic congestion in some areas.
The NBTC has given five mobile operators 15 days to resolve their dropped-call problem. The five are Advanced Info Service (AIS), Total Access Communication (DTAC), True Move, CAT Telecom and TOT Plc.
As of May, he said there were 994 complaints involving dropped calls for AIS, followed by DTAC (497), True Move (386), CAT Telecom (32) and TOT (seven).