The move, confirming speculation over the past couple of days that she would step down, was announced this morning.

In Telecom's media release announcing the move, Gattung is quoted as saying the telecom sector has 'a great outlook' and 'it has been a privilege to work in a company that is at the heart of such exciting change.'

Gattung said in the statement 'I am proud of the team I have worked with and I thank them for their support over all my time with the company."

Telecom chairman Wayne Boyd said a search for a new CEO has started and both internal and external candidates will be considered.

Boyd said 'we thank Theresa for her dedication to Telecom. She has built and maintained a high-performing team culture throughout the company and her energy, passion and intellect will be missed.'