Here is a neutral and interesting summary of the provided text in one paragraph: The guide explains how to combine Twilio Add-ons with Programmable Voice to use data from Twilio's partners in a Spring MVC web application. An add-on is a pre-integrated third-party service that enhances responses received from Twilio by including additional data from Twilio's partners. The IBM Watson Speech to Text Add-on can convert Twilio audio recordings into text using machine intelligence, and its data can be accessed through the "AddOns" field in HTTP requests made to an application. To use an add-on, it must be enabled in the Twilio Console, where users can select the add-on they want to install and set the callback URL and request method. The guide provides a sample code example that demonstrates how to access add-on data within a Spring MVC application, using the IBM Watson Speech to Text Add-on to generate transcription for recorded calls.