Cell phone number validation functions through various methods. Firstly, it checks the format of the number to ensure it follows a valid pattern. This helps in identifying any incorrect or incomplete numbers. Additionally, validators can also determine if a phone number is active by checking if it receives texts or calls. By sending test messages or making test calls, they can verify the functionality of a given phone number. This process is crucial in preventing wasted efforts, money, and time spent on invalid numbers. Tools like randommer.io offer reliable cell phone number validation services that help businesses maintain accurate contact databases and improve communication efficiency.