The Joomla extension XT Twilio for Joomla has been modified to add a first name field to the Contact by SMS module. The modification involves adding code to the module's template, JavaScript file, and PHP plugin file to support the new field. The changes enable users to input their first name when sending an SMS message, which is then sent with the rest of the message to the recipient's phone number via Twilio. The extension can be installed and configured on a Joomla website to provide a more personalized communication channel for customers.