The point is that it's not clear for me (I havn't found any doc pointing this) that it seens that the user need to have a 365 business plan. I have some user that only have a Microsoft Teams Essencial plan, for those user, I only get a 400 Bad Request response. I tryed an acccount with 365 business basic plan and the given code works fine. Graph API for online meeting only works for 365 business users? There's realy no other plans suport? Am I doing something wrong? Thanks and sorry for the problems.