Is the teams bot that auto calls and joins calls a paid service ?

@a-s -
Yes, you need an Azure subscription to register a bot with the Azure Bot Service. If you don't have a subscription yet, you can create a free account that provides access to various Azure services.
Ref Docs:

1. https://zcusa.951200.xyz/en-us/azure/bot-service/bot-service-quickstart-registration?view=azure-bot-service-4.0&tabs=userassigned
2. https://zcusa.951200.xyz/en-us/azure/bot-service/bot-service-quickstart-registration?view=azure-bot-service-4.0&tabs=userassigned

Thanks, 

Nivedipa

************************************************************************* 

If the response is helpful, please click "Accept Answer" and upvote it. You can share your feedback via Microsoft Teams Developer Feedback link. Click here to escalate.