- You can use the Graph Api to send messages in teams, see the documentation for details.
- Sending messages using the Graph Api is free, but requires an MS365 License. If you don't have a License, you need to try purchasing or free trial MS 365 license for your tenant, then go to Azure AD and grant that license to the logged in user.
- Yes, you can use Graph API to send messages directly. For details, please refer to the case in the document.
Hope this helps.
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