Employer calls employee's emergency contact to ask if he can come into work: 'Employer just called my mom to ask if I'd come in, because I didn't answer. I'm 30 years old.'

Not answering your phone on your day off does not constitute an emergency. 

Who do you have listed as your emergency contact? I always feel conflicted, because I could either put my mom or my roommate. I usually choose my roommate because if something happens to me, he can attend to the situation immediately, whereas my mom cannot, since we don't live in the same city. At the same time, I feel like my mom should be the first one to know if I have a horrible accident. I figure that either of them would make fine emergency contacts, but there's only one problem. I don't think my mom and my roommate have each other's contact information. It's probably advisable for your parent and your emergency contact to be able to correspond. Would it sound too neurotic to create a group chat with them and me just in case something bad happens to me? It probably should be a "cross that road when you get there" kind of thing, but what do you think? 

Luckily, I've never been in such a compromised state that I needed to call my emergency contact. There are very few situations that require such a call. If you're too sick or injured to get yourself home from work, your boss should call your emergency contact. It's all in the name. Unless there is an emergency, there is no reason to call someone's emergency contact. That's just common sense.