curl -X POST "https://demo.api.vultlocal.com/api/v1/external/whatsapp" \
  -H "Content-Type: application/json" \
  -d '{
    "event": "message",
    "message": "What is my balance?",
    "from": "23279648205@c.us",
    "phoneE164": "+23279648205"
  }'

{
  "answer": "Your balance is 5,000 SLE",
  "status": "success"
}

{
  "answer": "You are not registered. Reply with your full name to register.",
  "status": "success"
}

{
  "error": "Missing required field: message",
  "status": "error"
}