Onionphone is a native Android application for anonymous, end-to-end encrypted push-to-talk voice and text communication over the Tor network. No servers, no accounts, no phone numbers — your .onion address is your identity.
Cross-platform compatible with Terminalphone — call between Android and Linux/Termux using the same protocol.
Optionally use your connection as a relay for ephermeral group channels.
Find the release page for version 1.0.2 which supports custom bridges for accessing censored networks.
tor is actually a bit more secure than i2p from my understanding. mostly it has to do with the routing, which is both the strength and weakness of tor.