You'd have to know a modem pool to call and have an account there, I wouldn't even know where to start. Especially if I was already cut off from the Internet.
The question was asking about prep work that could have been done. Now is the time to print out some modem pools and get an account ;)
However, if you know someone technical out of the country, you can call them and ask them to set something up and get you the details. (Or you can't call them, and there you go).
If you're talking with people on things like Signal or WhatsApp, where phone numbers are user ids, you automatically know their phone number to call them in case the chat service is unreachable.
