Certain emergencies call for private conversations concerning only the student and the parent and no other bystanders should be able to hear what it is about. Some students might have bathroom emergencies in which they need pickup or something brought to them from a parent. Finally i think all students should have the privacy they all deserve to make private phone calls.
Some parents forgot or just are not in reach to get to a student in time for after school pickup. In cases like this students should be able to call a parent in cases like this. If students can not have contact with parents for pickup they could be waiting for hours because they simply do not have contact to a parent. Any students should not