The deal, which was inked with KAZ last year for IT and network support services, covers 90,000 desktops across 325 Defence sites in Australia as well as 24x7 support for its restricted and secret, IP-based, wide area networks.

While the department was unwilling to provide full details of the network support problems, a Defence spokesperson admitted the organization has been "inconvenienced" and is working to "address the underlying issues as quickly as possible".

The spokesperson said service delivery challenges with Telstra's ICT and IP services subsidiary have occurred due to "a sustained period of heightened Defence operational tempo" and network performance impacting a major transition to a new standard operating environment (SOE) for Defence networks.

As a result, KAZ has been forced to introduce "remediation" initiatives to stem the high volume of calls to the service desk.Compounding the problem is a skills shortage.

"[There are] difficulties being experienced by Defence and its industry partners securing and retaining ICT professionals," the spokesperson said.