If you have a server with PHP on it... you can use PHPmail and a script to trigger it... But it would require an arduino with an ethernet shield... or the arduino connected to the computer with the PHP server...
You can set some pre-written message, then tell the server to "email" it to your phone number... I know verizon it's (your number)@vtext.com and you'll get it as a text message.
Practically no one knows that you can email text messages, could someone abuse the crap out of it? Yes, they could... but no worse than someone can send a IM message to 123-456-1234, I know once I sent someone like 7 thousand text messages over the course of 5 or so minutes, thankfully this was before phone companies were assholes, they forgave him for the entire bill (well, beyond his normal bill)
It is easily connected to the arduino uno and will send and receive text messages which means you can coummincate with your arduino remotely through cell towers. How cool is that?
The dronecell is a cell that is designed to be connected to microprocessors such as the arduino.
you'll need an arduino + ethernet shield, and you're gonna have a secret URL on a php capable server
you'll also probably need the Prowlphp form github and change a few lines (API key)
im not exactly sure if this is going to be an SMS or an email, but its a notification nonetheless.