Hello Peter J,
Good day! Thank you for posting to Microsoft Community. We are happy to help you!
Based on the information you have shared with us; I understand you want to configure a bot through APIs to automatically join meeting participants by initiating a call to their Teams client just a minute before the meeting starts.
Base on the information you have shared with us this query requires extensive knowledge of APIs and Teams custom apps/bots development, unfortunately our team primarily handles queries related to Microsoft Teams standard functionalities.
We have another dedicated community where you will be able to find Experts with resources required for this particular query Microsoft Teams Developmentcommunity.
You can use the following link to post this query in the Microsoft Teams Development community: Microsoft Teams Development - Microsoft Q&A
Thank you for your understanding, I believe this will ensure faster and more accurate assistance for your specific scenario. Please do not hesitate if there is any concern or help you might need from our side, we will always do our best to assist you!