I have a ton of crap experience of this:
eg.
Vomiting child - projectile sick on carpet and diarrhoea: call mum's mobile, it's a dead line (she hasn't updated the school with a new number.)
Try dad's mobile; it's a dead line (he and mum have split up but apparently share share one mobile between them
)
Try next numbers on the list: aunty's landline; no reply and can't leave a message (no mobile no. given to school)
Granny; no reply on landline and can't leave a message (no mobile no. given to school)
Best friend: leave a message on landline (no mobile no. given to school)
So we have a very sick child, with a sick bucket and extremely upset, who a member of staff sits with away from everyone.
We finally had a phone call from the BF about two hours later.
The school takes a very dim view of this. It's not fair on staff, resources or more importantly the sick child.
The great thing about modern times, is, we DO have mobiles. Saying 'what did we all do before mobiles were invented ffs???...back in my day there were no mobiles ffs...' etc etc is a bit like saying 'we didn't have a cure for smallpox back then and everyone managed...'
It's simple: give your ds' s schools two or three rerliable contact number. Work. Mobiles. Exes, step-parents, grandparents..... then the school can ring, and stop wasting staff time and resources chasing up.