We could talk about RingCentral and how they are excellent in terms of their support of events like SunShinePHP.
If you are a WordPress developer, take a look at their APIs. It can run on PHP so it’s possible that you could write a plugin that can alert users or the admin of a WordPress site via SMS whenever ANYTHING happens. Site down? Text. A user is attempting to communicate on BuddyPress? SMS baby.
There are phone numbers involved. But something to keep in mind for your next PHP and WordPress project.