The exact same thing happened to me last week. My son got sick at school, enough so that they ended up calling the paramedics. But I had been spammed so much the week before with spoofed phone numbers from my area code that I had my phone on "Do Not Disturb" allowing only people in my contact list through. I thought it would be fine since the school's phone number is in my contact list.

Unfortunately the school's systems were down and so they weren't able to call me from the school's regular phone system. They called from random personal cell phones, so that went straight to voicemail. It wasn't until someone was literally sent to my house to bang on my door that I got notification of my child's medical emergency. They were about to administer medication that would NOT have been okay to give him, and I was lucky to be able to contact them and tell them to hold off before they did it.

Never mind reporting them to a phone provider. If something had happened to my son I swear to God I would have gone full Liam Neeson "what I do have are a very particular set of skills" on the jackass who's running that specific phone spam operation.