[id10t]

You want commercial or to roll your own solution?

Commercial wise, we use Blackboard's product for emergency notifications. Either doesn't work well at all, doesn't work with our weird setups, or the stuff that isn't working is due to policy/proceedure/etc on our end. But, a lot of large schools and such use it.

I've seen several open source projects that will send sms using a tethered phone of a certain type. Looks easy to set up, but I don't have the re$ource$ to play with to actually implement it and test it. Simple enough -receive some sort of authenticated message somehow, then start sending texts to whatever numbers in your db qualify. Need one of several certain type/models of phone with certain firmware versions, cell account for said phone on a carrier that allows sending messages like this, and after that it is basic programming/scripting to tie it all together.