The article explains how to validate international phone numbers in a Joomla extension using the Intl-tel-input plugin. The extension adds a flag dropdown to input fields, detects the user's country, displays relevant placeholder text, and provides formatting/validation methods. To integrate this plugin with the existing Click to Call module, the author modifies files that implement the module and adds new files from the Intl-tel-input plugin package. The modified extension is tested by entering valid and invalid phone numbers and confirming how the field detects the number pattern. The article concludes that receiving phone numbers in the right format and validating against country patterns is an essential layer of data verification, and further validation can be done using Twilio's Lookup API to reduce fraud and increase lead conversion.