Read the telstra value listed on their website
Know the essential requirements of the role and have the experience required for the senior role.
Have your answers ready. Be clear focus, and genuine
I would practice answering questions that are relatable to the work, such as why? what? when? and how?
Make sure you know what you are talking about
They use a pro-forma interview - get details from a contact who works there
Just like any other interview. Most questions asked are the same as other corporate ones.
Do some research on the company - prepare answers for some questions you may be asked.