More than one-in-five callers to Services Australia are left hanging on the telephone, with senior department officials admitting more needs to be done to reduce wait times.
Department heads told a Senate estimates hearing that of the 41 million calls made to Services Australia in the 2022/23 financial year, nine million were met with congestion messages.
Four million callers hung up before speaking with a Services Australia worker.
However, officials said they were not certain if the call drop outs were due to callers being frustrated with the long wait times or for other reasons.
While the department set a target of 70 per cent of calls made to Services Australia being answered within 15 minutes for the 2022/23 financial year, just 60 per cent of phone calls met the target times.
Acting chief executive Chris Birrer said the department would not revise the targets in light of the result.
"We would, of course, like to (meet the target) and we strive to do better than the result that we achieved last year," he told the hearing on Wednesday.
"If we get behind on processing claims, then it does generate more telephone calls, so part of our strategy at the moment is ... getting our performance in processing right so that it lowers the amount of phone calls that we're receiving."
Mr Birrer said while there were other ways for people to get in touch with Services Australia, such as online, most still preferred phone calls.
"Our preference would not to be delivering nine million congestion messages - our preference is to answer every call," he said.