Sprint is aiming to cut costs by up to $2.5 billion in the next six months and will freeze external hiring, according to a staff memo from CFO Tarek Robbiati leaked to the Wall Street Journal.

The memo says all expenses must now be reviewed and approved by the finance department in a bid to make savings of between $2bn and $2.5bn.

“When requesting to spend money take an owner’s mindset by treating every dollar as if it were your own,” Robbiati has told Sprint employees.

The memo comes at the end of a week that started with Sprint announcing it would not take part in the 600 MHz Incentive Auction scheduled for March 2016, explaining that its current spectrum holdings are sufficient to meet demand for existing and future. “Sprint has the spectrum it needs to deploy its network architecture of the future,” said Sprint CEO Marcelo Claure on Monday.

Sprint reports it has started a major effort to increase coverage and capacity by concentrating its network and increasing the number of cell sites using its existing spectrum. The operator is using carrier aggregation to get more out of its 2.5 GHz spectrum.

Sprint reported $7.5 billion of operating expenses in the quarter ending in 30 June 2016 and said it had cut $1.5 billion in costs in the previous 12 months.

In August Telecoms.com reported US operator Sprint has celebrated ‘meaningful progress’ in its corporate turnaround strategy by appointing a new CFO, COO and CTO.

Tarek Robbiati took over as CFO having previously run an Australian consumer finance company that specialised in leasing as well as senior positions at Aussie telco Telstra. Günther Ottendorfer took over as COO, technology, having previously been CTO at Telekon Austria Group, while John Saw was appointed as chief technology officer.

“Talented and experienced executives like Tarek and Günther will be critical to accelerating our efforts to move Sprint forward,” Claure said.