[yulker]

Legitimate callers for events you initiated leave messages. The correct avenue for critical notifications not initiated by you is still paper mail.

[RHSeeger]

But your child's school nurse might not, in an emergency.

[yulker]

Your child's school nurse would be exactly the type of person who would leave a message

[john_the_writer]

They might not.. But you'd very likely have their number saved on your phone. Might even have them as an un-mutable contact. My wife/kids and their school are all on the "never mute" list.