My company's policy is if you call out, you must do so at least 2 hours prior to the start of your shift. You must speak with your department manager or store management (I work as a pharmacy tech in a grocery store chain). I've only called out once in the 10 years I've been working here, right after my mother had back surgery, was at home, fell and hit her head; they wanted to check her for a concussion, and somebody had to meet her at the hospital to drive her home.