You can initiate a voice call in CakePHP using Twilio Programmable Voice by following these steps: Firstly, you need to have a voice-enabled phone number which you purchase from your Twilio account. Then, you bootstrap a new CakePHP application and install the Twilio PHP Helper Library. After that, you register environment variables with your Twilio credentials. Next, you create a template for rendering a form for entering the recipient's phone number. You also need to create a controller to handle the form submission where you use Twilio's PHP Helper Library to initiate a voice call to the entered phone number. Finally, you configure the route for the form action in your routes configuration and test that the application works.