I came across this interesting article during my daily readings. Another thread on this forum somewhat joked that with certain communication Apps being removed, some might need to communicate with wireless radios with coded phrases. This article lists some alternatives that might be used, if there was an Internet shutdown (either purposely or not), which currently seems to be occurring in the Country of India from time to time. These Apps would need to be downloaded to phones while the Internet was still available, but could then communicate without Internet access via Peer to Peer Networking using Bluetooth, and/or WiFi.
How to communicate when there's an internet shutdown?
FireChat, Bridgefy, Signal Offline, Vojer and Briar will help you connect offline
www.theweek.in