Must call, 2 hours out. Get harrased by schedulers as to why you have called in sick and what you need to do now. Then realize that if you have called in sick (or any other reason you cannot make it to work) more than 3 times in a year it will go on file and you will get a nice little email from the company. 5 times in a year, be ready for a meeting with the company on how you suck as employee. No donut for you.
Just one more thing to explain to your next employer when they check out your record during the application process.
I guess its working real well too.