Optus has lifted its quarterly net profit by more than 40 per cent, but concedes it still needs to address network coverage and bill shock.

Optus boss Kevin Russell says the telco is also working to improve customer satisfaction as complaints to the Telecommunications Industry Ombudsman dropped to around 1000 in the December quarter, the lowest rate in a decade.

“Satisfied is absolutely not where we are,” Mr Russell told reporters after the company’s quarterly results were released on Thursday.

“We’ll continue to push hard to improve the service.”

Mr Russell said billing remained a challenge for the Singapore Telecommunications-owned telco which was working to address roaming and data bill shock.

“Expect to see improvements in both of those areas,” Mr Russell said.

He added that Optus’ network quality would improve substantially once the company was given access to additional spectrum.

Optus made a net profit of $227 million for the three months to December 31, up from $160 million for the same period a year ago.

That was despite a five per cent slide in revenue, which Optus attributed to a mandated reduction in termination fees, lower equipment revenues and service credits associated with device repayment plans.

As well as lifting profit growth the company was regaining market share, despite a slide in revenue from mobile customers.

Mr Russell added that customer complaints about the network had halved over the past 12 to 18 months.

The number of customers on its 4G network rose more than 30 per cent during the quarter to 1.8 million.

Optus is expanding its 4G network to cover 70 per cent of Australia’s metro population by April 2014.

“We’re seeing improvements in terms of 4G satisfaction levels and 4G uptake,” he said.

The company is focused on delivering sustainable profit growth and making significant improvements in the customer experience.

Singapore Telecommunications shares were six cents, or 1.9 per cent, higher at $3.15 at 1503 AEDT.