Communicating without Cellular Networks
What is mesh messaging or off-the-grid messaging?
Peer-to-peer networking systems that allows users to contact each other without relying on the cell or WiFi networks, or any other government-controlled infrastructure. This only works well at close distances (within 100m max) and works better when there are more individuals whose phones can be used to exchange information and expand that bubble of connectivity.
Platforms to use with/without internet
Bridgefy enables you to send offline messages without access to the Internet by turning on Bluetooth. (Android and iOS)
Signal Offline Messenger enables users to communicate without internet or local network in a range of up to 100 meters. (Android only)
FM Radio Apps uses a headphone cable to act as an FM radio antenna.
Navigating without GPS Technology
How to disappear from the Internet: