How to update a webpage via sms text messaging (NON wordpress)

I want to update a webpage by submitting the content via sms text messaging from my phone, to my website. Similar to the way a wordpress blog would be able to, but this is a static, NON Wordpress website.

Any thoughts on how I can use PHP to achieve this?

I include my content via PHP on each 'index.php' file as such:

<!-- include the specific content for a page... -->
    <?php 
        // depending on where we're at, include that specific file...
        if($location == "/") {
            include($_SERVER['DOCUMENT_ROOT'].'/content.php');
            } elseif($location == "/articles-blog/") {
                    include($_SERVER['DOCUMENT_ROOT'].'/articles-blog/blog.php');

So I'd like to be able to include content submitted via sms text messaging (into the "blog.php" file).

Thanks & Best Regards