The benefits of Centrelink's multimillion dollar contracts with private call centre operators are unclear despite claims a secret, independent report found contractors answered more calls than public servants, the national auditor says.
Human Services Minister Michael Keenan overseeing the agency has lauded its use of Serco to answer calls from welfare recipients, but the Australian National Audit Office said falls in busy signals may have other causes.
The Coalition government has previously said a review by consultants KPMG, which it has refused to release arguing it is a confidential cabinet document, showed the 250 contractors answered more calls to Centrelink than public servants during the pilot.
An audit of Centrelink's phone services released on Thursday found it was unclear what impact the agency had achieved by resorting to private contractors to reverse its deteriorating results.
Seasonal variations, policy changes, and other Human Services Department projects to improve services may also have influenced the results, the audit office said.
The finding casts doubt on government claims its $53 million pilot contract with Serco would cut its engaged signals, used to justify a decision to outsource more work to private call centre staff and bring their total to 2750 by April 2019.
"There are a number of factors, such as seasonal factors and policy announcements, which influence the overall volume of calls and therefore the incidence of call blocking," the audit office said.
Its analysis of Centrelink's phone services showed the number of busy signals fluctuated throughout the year and had continued to fluctuate since the welfare agency began the Serco pilot in October 2017.
The agency's reporting to its executive also failed to give full insight into customers' overall experience, such as the time spent waiting before they abandoned calls or the number of calls answered within specific timeframes, the report said.
"This information would support Human Services to continue improvements in the telephony channel and the transition to digital services," the auditor said.
The Human Services Department did not appropriately report its phone service performance to the public, failing to provide a clear understanding of the service a customer could expect.
The auditor also found Centrelink needed to improve how it monitored customers' migration to its digital services, saying it was failing to measure how effective this was and how it was affecting its other work.
"Human Services has identified a need to improve indicators in this area and is working to address these limitations," it said.
The Human Services Department said it has improved how it monitored and reported its results in letting its executive leadership team better track its transition to more digital services.
It said it was reviewing its performance measures for phone services.
Mr Keenan's defence of his agency's growing contractor use was met in October with scepticism as the main public sector union and Labor questioned the number of customer queries resolved by private workers.
As the Coalition refused to release the report for public viewing, any other findings have remained confidential despite Mr Keenan drawing on details to argue for its spending on contractors.