Well, my folks live/visit countries with insane govt censorship, so it was quite easy: I just said our private XMPP server is a good reserve comms channel, and over time they just got used to the peace of mind that it gives to them. Decent android (https://f-droid.org/en/packages/eu.siacs.conversations/) + web (https://github.com/nioc/xmpp-web) clients played vital role though. Also, shout out to Delta Chat! (https://f-droid.org/packages/com.b44t.messenger/)