The Australian economy continues to be patchy but small to medium businesses appears to have turned the corner, Telstra chief executive David Thodey says.

Telstra, which added more than 600,000 new local mobile customers in the last six months of 2012, said it had experienced an improvement in sentiment in January as businesses made more investments.

"The general sense of the economy is it's still patchy," Mr Thodey told reporters on Thursday.

"We're seeing a little bit more life in small to medium business."

Telstra's own surveys revealed more confidence appearing in that sector.

However, Mr Thodey said Telstra's business was not as dependent on the economy as some other businesses.

"It's such a critical service people have," he said.

"Consumer confidence was a little bit slower going into Christmas, but January was strong and in the enterprise market you've still got companies making big investments."

The retail sector was slow but financial services were looking at innovative ways to run their businesses.

"It's very mixed, so you can't get a complete sense of what, in other years, we've been able to really talk about, but in general it's steady as we go in my view."

He said that nothing had changed for Telstra in terms of the National Broadband Network.

"We have legislation and a contract in place and that's what we're focused on.

"We talk to all sides of politics as you'd expect, but nothing has changed."

Telstra shares rose on Thursday after the telco lifted its first-half profit and said it was on track to achieve its full-year growth targets.

The company recorded a net profit of $1.6 billion in the six months to December 31, up almost nine per cent on $1.47 billion in the same period in the previous year.

AT 1245 AEDT Telstra shares were 7.5 cents higher at $4.65.