curl --request GET \
  --url https://api.openphone.com/v1/call-voicemails/{callId} \
  --header 'Authorization: <api-key>'

{
  "data": {
    "duration": 60,
    "id": "<string>",
    "transcript": "Hello, this is a voicemail from John Doe.",
    "recordingUrl": "https://examplestorage.com/a643d4d3e1484fcc8b721627284eda5e.mp3"
  }
}