I've been trying to figure this out for close to a year now, and haven't made any headway so I'm hoping you guys can help with some suggestions.

I regularly get texts from places like Walgreens or my bank, letting me know when something is ready. There's an opt-in in the beginning, and after that they just send a brief text when appropriate.

I want to set up something like that on my end. I have a virtual server with Softlayer, running CentOS 6.x (although I know I'll have to update to 7.x within the next year). Since there doesn't seem to be any way to push a notification to their phone from a website, my second choice is to set it up so that when a user gets a Private Message, the server will send them a text alert.

Can you guys suggest any way to set this up? I mostly load pages in PHP and jQuery, and process form submissions in Perl, but I can work with pretty much anything.