Telstra has announced plans to cut up to 2800 jobs - equivalent to 9 per cent of its workforce - as part of a "reset" of its Enterprise business.
Most of the job losses would happen by the end of this year, and would involve consultation with employees and trade unions, the company said.
Telstra Chief Executive Vicki Brady said the move was required to ensure the company could continue to make the investments needed to support the increasing growth in data volumes and "deliver improved connectivity for customers across the country".
"I appreciate the uncertainty proposed changes like this can create for our people and we will support them through this change with care and transparency," Brady said.
"As we propose specific changes, we will talk them through with our teams and union representatives first."
Brady said the reduction in its workforce would save the company $350 million.
She said the job cuts were "difficult" but "necessary" as parts of Telstra were not performing to the required levels.
"We need to be a more efficient and sustainable business to ensure we can keep investing at the levels required to meet the ever-increasing demand for our connectivity and services for our customers right across the country," she said.
Talks would begin today with some of the impacted staff, Brady said.
"Consultation with employees will commence today on 377 of those proposed job reductions.
"We will continue to work through the detail as fast as we can on the remaining proposed changes and I anticipate being able to update our employees around mid-July."
Brady insisted customer service would not be affected by the job losses.
"We're very focused as we make these changes. We have invested significantly in our customer service over recent years," she said.
"That includes on-shoring our call centres for consumer and small business customers, it includes buying back our stores to deliver a consistently good experience.
"None of these changes impact those commitments. As we work through the further changes still to come that I expect to be able to share with our employees in mid-July, customer service and experience will continue to be a key priority in that."
The Communication Workers Union (CWU) described the job cuts as a "national disgrace" and said the standard of service to Telstra customers would be impacted as a result.
"You can't axe 2800 jobs and not expect it to have an impact on service delivery," said CWU national assistant secretary James Perkins.
"While the detail of where exactly these jobs are being cut from is still unclear, one thing is certain – it will have a devastating impact on services.
"You can't slash thousands of jobs without seriously impacting the delivery of services across the country. Telstra has to answer to this."
He said the announcement of the job losses had come "completely come out of the blue" for the thousands of affected Telstra workers.
The CWU said it will be seeking meetings with the company and providing as much support as possible to workers.
