I installed ejabberd + Gajim on Windows PCs + Xabber on Android phones.
Chat is working flawlessly. Now I would like to transfer files between all the clients.
Surprisingly I found out that for Xabber there are some additional things needed like HTTP proxy etc...
But file transfer between Gajim clients works without any additional installations and additional servers! And all these clients use XMPP.
Is there some standard means to transfer files with Jabber which all the clients support?