I’m using the uptime monitoring service, which requires your site to have a certain URL that will return “success” if everything looks fine.

With that in place, go create an account at Clickatell or a similar SMS gateway. Folks in the US needn’t do this, because SMSes are paid for by the recipient, not the sender, but here, you have to use a gateway so you have someone to pay.

Now, finally, go to uptime and use the email sms@messaging.clickatell.com. Once created, go edit the parameters. Choose Periodic, and enter the following body for the email, using your own values for the different fields:

api_id:XXX
user:yourusername
password:yourpassword
to:yourcellnumber
text:Yoursite.net is down

That’s it, you can now look forward to getting SMS messages in the middle of the night. Enjoy! (Thanks to Claus Rasmussen for pointing me to clickatell.)