Gattung worked in senior marketing roles at National Mutual and at the Bank of New Zealand before taking up a similar role at Telecom New Zealand. In April 1996, she became Telecom's Group General Manager Services. In October 1999, she took over from Rod Deane as Telecom's CEO of the telecommunications business with a $5billion turnover operating in New Zealand and Australia and listed on the NZX, ASX and NYSE. Gattung was the first woman to run a large New Zealand public company.