Sending an SMS using the Twilio API with Java requires some setup, including installing Java 8 or newer, a Java IDE like IntelliJ IDEA, and a Twilio account. Using the Apache Maven build tool can simplify this process by downloading and managing dependencies. To create a new project, start by creating a pom.xml file with the necessary configuration, including specifying Java 8 as the target version and the Twilio Helper Library as a dependency. Then, write a Java class called TwilioSendSms in the src/main/java directory, which will authenticate the Twilio client and call the API to send an SMS using environment variables for sensitive information like ACCOUNT_SID and AUTH_TOKEN. Once this code is written, running it can successfully send an SMS with the specified phone numbers.