curl --request POST \
  --url https://api.hubapi.com/crm/v3/extensions/calling/transcripts \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "engagementId": 123,
  "transcriptCreateUtterances": [
    {
      "endTimeMillis": 123,
      "speaker": {
        "id": "<string>",
        "name": "<string>",
        "email": "<string>"
      },
      "startTimeMillis": 123,
      "text": "<string>",
      "languageCode": "<string>"
    }
  ]
}
'

{
  "id": "<string>"
}