Amazon makes it really easy to send SMS messages worldwide using their SNS or Simple Notification Service. This tutorial shows you how you can send a SMS in less than 10 lines of code. This particular example uses composer to install the AWS SDK.
I’ve been experimenting with the Twilio API recently and have found it very easy to automatically send text messages or call a telephone programatically. In fact, you are able to send a text message in just a few lines of code.