Not to be confused with Teams meetings, calls in Microsoft Teams are initiated from the "Chat" section of the app, and are inherently more private than meetings. Calls are always started on-demand, and so they don't ever appear on a calendar, and when you join a call, there is no "join link" that you can send to others, which is how Read joins all meetings. Unfortunately, this means that Read is not currently able to join Teams calls as a participant and record that way (but it can record Teams meetings, either by connecting your calendar and configuring your join preferences, or by adding it manually).
Alternatively, you can use Read's desktop app to record Teams Calls. If you don't use our desktop app, but are able to obtain a recording of the call through some other method, you should be able to upload the file to Read in order to generate a report that way.