Openfire crossdomain communication

I have two App, one is for internal employee, another is for customer. I have two message servers (which uses openfire) for the two App. How do I configure the two openfire to talk to each other?

For example, since customer app and employee connects to different openfire, How can a customer inits a conversation to an employee?

Check the Server to server menu in Admin Console. You should enable it on both server’s and each other to white list.