If you mean to say that during a conference, a Jabber user cannot hear any voice from other parties, while the other parties can hear everyone including the Jabber user, here are some steps to troubleshoot:
Check Conference Resource: Ensure that the conference resource being used can reach the Jabber user. Verify that the Jabber user is correctly connected to the conference bridge or resource.
Network and Route Issues: One-way audio issues are often caused by network or route problems. Investigate the network connectivity between the Jabber user and the conference resource. Check for any firewalls, NAT, or routing issues that might be affecting audio traffic.
