baresip+

VoIP User Agent app for Android based on baresip SIP library

Quicksy

Jabber/XMPP with Easy Entry and Easy Discovery

Conversations

Encrypted, easy-to-use XMPP instant messenger for your mobile device

Session F-Droid

Encrypted private messenger

TRIfA

TRIfA Tox Client

baresip

VoIP User Agent app for Android based on baresip SIP library

Nextcloud Talk

Have private video calls and chat using your own server.

Element X - Secure Chat & Call

Sovereign. Seamless. On Matrix

Wire • Secure Messenger

Wire offers highly secure communication – anywhere and anytime.

Jami

Share, freely and privately

monocles chat

is a secure XMPP chat client for Android

Linphone - open source SIP client

SIP (VOIP) phone

aTalk

XMPP/Jabber client with encrypted instant messaging and video calls

Threema Libre

Secure and private messaging

SimpleX Chat

SimpleX Chat - e2e encrypted messenger without any user IDs - private by design!

Jitsi Meet

Instant video conferences efficiently adapting to your scale

Cheogram

Chat on the Jabber network (XMPP protocol); focus on features for gateway users

Element - Secure Messenger

Group messenger - encrypted messaging, group chat and video calls

Meshenger

Voice- and video phone App for off-the-grid scenarios.

ThreatScoopOnionChat

A Forked Version focused on privacy from SESSION

Mumla

Voice chat on Mumble servers

another.im

Yet Another Conversations fork but...

aTox

aTox, a beautiful and modern Tox client

Sipdroid

A SIP (VOIP) client

Databag

A federated chat client designed for privacy and selfhosting.

Snikket

StoneAge

A self-hosted P2P messenger - you will need an S3 bucket to use it

unofficial Stud.IP-app

An unofficial app for Stud.IP systems.

Lumicall

SIP softphone