Sending an SMS with PHP and Twilio requires just a few lines of code and can be achieved by signing up for a free Twilio account, buying a phone number, installing the PHP helper library, and using it to create a new message from the Twilio number. The process involves including the helper library, creating a Twilio client using account credentials, and sending a message with a specified destination phone number and body. Once completed, saving the file and running it will result in receiving an SMS on the designated phone number.