Citing industry debate over the cost benefits of the practice, McNamee believes outsourcing comes at the expense of improving in-house skills, which might reduce those costs over time.
"This whole relationship between the 'keep the business running' costs, and the process improvement costs, is a key issue that you've got to address," McNamee told attendees at the IT Financial Management conference in Sydney.
"I reckon when you outsource you basically set a cost line for a whole function. And the whole reason why the outsourcer is in business is that he doesn't make any money for the first two years of the contract, but then he uses technology, and process improvement internally, to make that profitable transaction. And that's what you've given up," he said.
Process improvement costs could be staff training or projects like server consolidation, which lowered fixed costs and made the business more profitable, according to McNamee.
"So you really have to get onto this bandwagon, which is taking infrastructure and commodity services down constantly ... you've gotta get on the bandwagon of saying today we can use technology to our financial advantage."
Coca-Cola uses a 'process improvement' framework for its technology department, whereby services are constantly evaluated and refined, in order to improve. The company "doesn't believe in outsourcing", according to McNamee, saying "you shouldn't be relying on suppliers to do your major projects".
This year the department halved its contractor numbers and hired around 40 internal staff, according to McNamee. The company has a total technology staff of 300.
Consultants were "too bloody expensive, and they don't know your business well enough", McNamee told ZDNet Australia in a telephone interview.
He offered two examples of how the focus on in-house skills continually lowered costs.
"We paid eight cents two years ago for all local calls. Today we pay four cents per call in Australia. Your telecommunications should be 50 percent today of what they were two years ago. If someone in your IT department's not driving it, you're not building capacity for process improvement."
"So do your PCs cost you 20 to 30 percent less today than they did two years ago? If they're not, someone's not doing their job. You've gotta drive down the cost of infrastructure to create capacity and headroom for process improvement," he said.
However McNamee did not rule out outsourcing on a smaller scale. Hosted services, for instance, could be used to manage infrastructure which wasn't crucial to the core business, and help focus internal resources on competitive functions, he said.
"Whatever happens you've got to have a 'near one core' application. I don't care whether it's SAP or something else. But ... functionality, you don't want to invent. You better have it from some external organisation that's going to innovate.
"I don't want to hear about IT people working on accounts receivable, or debt collection, or audited cash processes. That's not where you differentiate yourself from the market.
"You can build your core competencies around the services layer," he said.