curl --request GET \
  --url https://api.ravan.ai/api/v1/contacts/{id}/calls/stats \
  --header 'X-Api-Key: <api-key>'

{
  "success": true,
  "message": "<string>",
  "data": {
    "total_calls": 123,
    "total_duration_sec": 123,
    "avg_duration_sec": 123,
    "last_call_at": "<string>"
  }
}