I am running an ejabberd XMPP server, and I am using Coccinella for chat with other users.
Users are running windows.
How can I enable the "Call" button on the chat window? Do I have to configure ejabberd for this?
VoIP is peer-to-peer and thus it does not need any specific server configuration. Maybe it has something to do with your network setup, firewall,...? Are you sure your contacts also run Coccinella as you do? Do you see the phone icon(s) next to the people in your contacts list?