Return Busy status on OOH323 for failover

I have an working setup between an Asterisk and Alcatel OmniPCX via ooh323.
I receive the calls on a local queue on asterisk but now I need to send back a specific status to Alcatel when there are no agents available on the queue (and don’t answer the call because that will mean an occupied channel).
I know how to bypass the queue based on status (if ("${QUEUESTATUS}" != “JOINEMPTY”) {) but if I simply HangUp or send Busy the call ends to asterisk and the call cannot be forwarded to another internal Alcatel extension for failover.

Please advise.