[ImPostingOnHN]

A school nurse is certainly expected to leave a message with a callback number. There are hundreds of millions of ways to leave a callback number that isn't 1 specific number you want. But "leave nothing" obviously isn't an acceptable solution, and leaving a personal cell number as a callback is a more acceptable one.

tl;dr: leave message+number, how you do so is up to you

[organsnyder]

Absolutely. The person I was replying to said that voicemail was not a reasonable option. If the nurse needed to send an SMS their only option may be to use a personal device, and it isn't reasonable to expect educators and staff to provide personal contact information to parents.

The proper procedure is for the nurse to leave a voicemail with their school-provided contact number (either the school office or a way to dial them directly that isn't their personal number).

[matsemann]

However, since voice mail isn't common where I live, I also get all communication through text. Most systems send out texts. It's how I communicate with the plumber, my dentist etc. Basically never talk over phone with anyone.