This guide shows how to block spam calls and robocalls using the Twilio Marketplace and Ruby skills. It starts by integrating third-party technologies, such as Marchex Clean Call and Nomorobo Spam Score, into the Twilio API. The code uses these Add-ons to check the phone number score of incoming calls and reject or accept them based on the advice provided by each Add-on. The guide also covers call handling options, rejection options, and configuring a phone number webhook. It provides example code and unit tests to test blocked calls and demonstrates how to use Twilio's Add-ons Marketplace to extend Twilio apps.