A Centrelink call-centre employee has told of working days filled with threats, abuse, unpaid overtime and desperate attempts to help clients in trouble.

The public servant, stung by online attacks on her and her colleagues in the wake of the Auditor-General's revelations of Centrelink's shocking record of answering the phone, says she and her co-workers do their best under very tough circumstances.

The Australian National Audit Office's report shows how the numbers of public servants answering phones for the welfare agency was slashed by more than 25 per cent in six years while the number of calls they were expected to answer increased by more than 10 million a year.

But it is the voice on the end of the phone that often bears the brunt of clients' frustrations, according to the worker, who cannot be identified publicly.

Describing one recent day at the office, she told how she had "worked an extra unpaid hour to complete a claim for a customer".

"Last count got abused and sworn at eight times, that's a good day.

"Granted five payments, referred a customer to a social worker, for DV [domestic violence], answered 48 calls and helped each customer in every way I could."

Centrelink Smartcentre workers are a long way from the stereotype of Canberra's public service elite: the operators are more likely to be mothers, work part-time or casually, and be based in regional Australia than nearly any other group of public servants.

The audit report revealed the number of "service officers" employed by Centrelink has dwindled from 3891 in 2009-10 to just 2743 in 2013-14.

But during the same period, the number of customer phone calls that actually git through to Centrelink's telephony system surged from 32.7 million to 43.7 million.

The service officer said the pressure on her and her colleagues was demoralising.

She said she and her co-workers often worked late, without being offered flexi-time by their bosses, to help clients who were having trouble.

"We don't get flexi days we work over our allocated shift helping people ... after being abused most days," she said.

"I am only a mother, a person just like you.

"I love my job and do my absolute best every day, like everyone I know at the Department of Human Services.

"Don't blame the staff, we are there to help you but with all the cuts our job is getting more difficult.

"We don't make the policy or legislation we deliver it."