Kindly note that Microsoft Q&A forum mainly focus on Teams general usage questions. If possible, please consider contacting support in Microsoft 365 admin center>Support>New service request to have them look into this issue.
Response code 487 indicates that the previous request was terminated by a user or application action. This can happen when the call is canceled, dropped, or times out. Some possible causes are:
The caller or callee hangs up before answering the call.
The call is forked to multiple endpoints, and one endpoint accepts the call, resulting in a 487 response from the other endpoint.
The call is blocked by a firewall, proxy, or session border controller (SBC) due to policy or configuration issues.
To resolve this issue, you may need to check the SBC and see if there are any errors or warnings. You may also need to contact your service provider or vendor for assistance.
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