This probably works well in elementary school, but in high school just "calling in" is typically not an excused absence and students are not allowed to make up the work for an unexcused absence and it is recorded as a zero.
This isn't an elementary policy or practice, it's the view the state has on truancy. Meaning it is very hard to prosecute a parent who is making the effort to work with the school and letting them know their child won't be in school. There is also an unwritten rule of thumb in our area that says for someone to be truant they need to be absent unexcused for about 20% of the time.
Any teacher or educational facility that wouldn't allow someon to make up missed work, excused or not, is not much of an educator. If the work was important to assign in the first place and is valuable to the student in the process of learning they should be given the work. What kind of an educator 'punishes' someone with ignorance for missing a day of school. I certainly hope this teacher is held to the same standard as their students and does NOT receive a paycheck when they are absent (using the same criteria for excused/unexcused absences).
I'd be interested as to what is an excused absence. If calling in isnt acceptable then they must require a doctors note? Unrealistic to think that every time someone is sick they have to go to the doctor or risk getting zeros.