Hello,
Thank you for posting in Q&A forum.
As a user from the Teams client settings (which you can access by clicking on the 3 dots next to your profile pic at the top right of Teams) you can modify your call answering settings as shown below.
A better option though would be to ask your admin to set the busy on busy options in the teams calling policy as per -
Configure calling policies in Microsoft Teams - Microsoft Teams | Microsoft Learn
Best regards,
Jill Zhou
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