Three rounds: Initial call with introduction to the company, position, any first questions from the application/job description. Second call with manager, more questions asked (behavioural/situation), as well as questions on the role itself. Third round: call with manager and two heads of the company, asking them questions about the company, it's values, what would be expected of me. More a chat then anything else, to check you are a culture fit, make sure you understand the vision of the company.