curl --request GET \
  --url https://your-instance.example.com/api/calls/voice-ai/voices \
  --header 'Authorization: Bearer <token>'

{
  "voices": [
    {
      "voice_id": "21m00Tcm4TlvDq8ikWAM",
      "name": "Rachel",
      "labels": {
        "accent": "american",
        "age": "young"
      }
    }
  ]
}