Now I only can select that an email is send to me when one of our environments goes down. But this mail will not always directly be read. I would like to be able to receive an SMS warning on my phone so I can directly take action and investigate what is going on with that environment.
True, but our model is already big and it should be simple also for novice users.
I would start using a logging module which stores all the system log in the database. When critical event is committed to the database you can use a SMS service to send a message to you mobile. Using own functionality you can configure the text message the way you want.