This app was mentioned in 12 comments, with an average of 1.50 upvotes
I use Xabber via Arc Welder. Limited to XMPP however.
Another alternative is xabber, its development slowed down in the last few years, but I still use it out of habit with no problems.
Edit: oh, and it's free software just like Conversations.
A very nice, free, open-source Jabber client: Xabber
And the mother of all Android VoIP/SIP programms: [CSipSiple](https://play.google.com/store/apps/details?id=com.csipsimple] Free, open-source.
Unreal server is available already packaged for most of operating systems, like on FreeBSD you could do pkg install unreal.
Personally I use unreal under FreeBSD.
Of course is a syncronous service, which means you need to stay connected.I'm not sure how much it will consume, since you aren't transmitting/receiving so much, and most of mobile devices are decreasing the power when not transmitting and only doing the Location Update to the HLR/VLR.
If you want queuing, XMPP server + Xabber
(https://play.google.com/store/apps/details?id=com.xabber.android ) is not consuming that much energy on my phone.
I am using jabberd2 with Xabber/Pidgin/Psi+ and I don't have problem on the android battery on my Samsung S4.
About "secure": your server is as secure as good your sysadmin is. There is no technology which can grant security to an incompetent sysadmin.
If you haven't a skilled sysadmin available, I simply don't suggest self-hosting. I don't want to be rude, don't take me wrong, but self-hosting will cost you a continuous monitoring, upgrade, patch, keep in touch with new vulnerabilities, and so on....
I'm talking android, not no dirty Apple crap. Maybe we should take a collection to pay Pidgin to create a mobile app. Or make our own app? I am sure we have enough code savy people. Has anyone tried this:
https://play.google.com/store/apps/details?id=com.xabber.android&hl=en
I used Xabber for a while but even back then it's UI was already out of date.
Sadly I don't know of anybody who still uses Jabber. It's always been just few people. IRC seems to be dead for me as well. Oh, ye olde times...
In addition to the ones /u/Natanael_L mentioned, there's Xabber. Find a server provider such as DuckDuckGo or FastMail.
> Jabber / XMPP - sehr variabel, viele Möglichkeiten zur Konfiguration, allerdings deutlich weniger Nutzerfreundlich als Signal
Unkomplizierte Freie Software Lösungen mit OTR-Verschlüsselung:
Für iOS kenne ich keine Option.
Xabber is free (as in beer and speech) and supports OTR, although it has not been updated since 2015.