Crypto telegram groups is the best choice for private channels. I used ejabberd 4.1 (also as the second best choice) and may have been using 4.0.x. Not sure what version of any of the chat clients you used or if you could even get the right version with you or it just was not available. You can use irc.freenode.net, TeamSpeak, or you could use virc and see if it is working in your local IRC network. If you use it in IRC, it does not need to be running and you could even pull the logs when you start the nagios instance. I used virc on Linux as it has end to end support for VNC remote connections.