curl --request GET \
  --url https://api.example.com/api/token_usage/{call_id}

{
  "call_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "token_usage": {
    "stt": {
      "total_audio_seconds": 0,
      "total_audio_tokens": 0
    },
    "llm": {
      "prompt_tokens": 0,
      "completion_tokens": 0,
      "total_tokens": 0
    },
    "tts": {
      "total_characters": 0,
      "total_tts_tokens": 0
    }
  }
}