17510: Invalid participant count

Twilio could not create the transcription because the participant count is invalid.

• If the request specifies sourceId, you can provide either 0 or 2 participants.
• If the request specifies mediaUrl together with a Conversation configuration, you must provide exactly 2 participants.

• Supplying only 1 participant
• Supplying more than 2 participants

• For mediaUrl requests that use a Conversation configuration, provide exactly 2 participants—one per audio channel.
• For sourceId requests, either omit the participants array or provide exactly 2 participants.

• Specify participant information