I got to thinking that there's not going to be much mobile phone service in many places, but there's probably still pay phones around. So I bought a prepaid card, and felt a bit retro about it--I think the last time I bought one of these cards was when I bought an MCI card for my trips to the Boy Scout National Jamboree in the 1980s, or maybe in 1995 for my motorcycling trip to Calgary.
I got this card: https://attprepaidcard.amssupport.net/
Anyways, 300 minutes for $18... plus whatever the payphone operator charges, up to 70 cents a call. Sure, I'll do it, but I feel a bit retro about it.