[Freeswitch-users] Chat message to unregistered user currently in conference room

Hi, I tested the chat command via cli to send a *registered* sip user a message. Works fine. (as described here: https://wiki.freeswitch.org/wiki/Misc._Dialplan_Tools_chat) Is it possible to send a user, who is currently in a conference room on my freeswitch server, a chat message if this user is *not* registered? In the cli I receive "Sent" but the message does not reach the client (check via sip debg log on the client). Thanks in advance, Thorsten