One could hand off the messages to a Morse operator (or what have you) on just about any network, to include some set up after major EMP events, survivors of th

One could hand off the messages to a Morse operator (or what have you) on just about any network, to include some set up after major EMP events, survivors of the events, or some immune to their effects — e.g. print the message out and send it by carrier pigeon or runner, use a heliograph [0], etc. The important thing is that your encryptor still works. [0] https://en.wikipedia.org/wiki/Heliograph https://en.wikipedia.org/wiki/Heliograph