Sending one-time passwords via WhatsApp using PHP, Laravel, and the Twilio API for WhatsApp allows businesses to engage with customers securely and in real-time. To achieve this, developers need to set up a database, install the Twilio SDK, and modify the registration logic to include generating an OTP at the time of registration and delivering it via the Twilio API for WhatsApp. The application should then update the view to include the phone_number field in the registration form. Testing involves running the application with `php artisan serve` and navigating to the registration page to send an OTP, which will result in a WhatsApp message shortly with the OTP.