The only one I really remember is Trogdor, but in order to keep it in my heart, I am a proud owner of Trogdor!!: The Boardgame

Depending on the complexity, there’s also abbrev-mode: https://www.gnu.org/software/emacs/manual/html_node/emacs/Abbrevs.html

There’s a fork of Openboard that is trying to update it, but AFAIK, it’s not published anywhere yet: https://github.com/Helium314/openboard

Thanks! I found the instructions here, which don’t seem too hard: https://blog.voip.ms/voip-on-cell-phones-ios-and-android/

But otherwise, VoIP.ms looks pretty much like what I’m looking for. It also seems super super cheap for my needs (keep a phone number alive, make a few calls or SMSes per year).