API To Retrieve All Call Activity For An Organization

We need to export records of all the calls made in an organization on a daily basis for our BI system to cross-reference the records with other related data sources. So far, I can only find an API method to retrieve all the users who had call activity on a particular day, and then I need to query each user's details individually. This data is available through reports for both SMS and Call activity, so why is it not available through the API?