Can You Be Fired For Calling In Sick -- Even With A Doctor's Note?

sick note miss work
sick note miss work

I recently received this question from a reader:

Q: I have missed about a week and half of work due to being really sick. I can barely talk and have no voice. Keep in mind here my job is a telesales rep. I call people all day. Are they legally able to fire me even though I have a doctor's note every day I missed?