16099: Unexpected conference status

This error means the conference is not in the status required for the operation you're trying to perform. A conference can be init, in-progress, or completed, and participant actions only apply to active, in-progress conferences. Use statusCallback to track conference and participant state changes instead of polling.

• You tried to manage a participant after the conference had already ended. The Participant subresource only manages active participants of in-progress conferences, and ended conferences do not return associated participants.
• You tried to act on the conference before it reached in-progress. A conference is created when the first participant connects, but it does not start until the second participant joins or a moderator joins, if one is configured.
• You identified the conference by friendly_name and matched the wrong instance. Multiple conferences can share the same friendly_name, and only one of those conferences can be in-progress at a time.

• Wait until the conference is in-progress before adding, muting, removing, or inspecting participants. Use statusCallback to react to conference and participant changes.
• Use the specific ConferenceSid for the conference instance you want to manage. Do not rely on friendly_name when more than one conference can exist with the same name.
• If the conference has already ended, capture participant details from statusCallback or use the Voice Insights API for post-call participant data.

• Conferences resource
• Conferences Participants subresource