A PMS system is what a hotel uses to manage the property and at the same time pass and receive information from various subsystems such as the telephone system, movie service and others for automated management and posting of charges into a guest folio.
In this case, the PMS system would normally provide the guest name to the PBX and at the same time unblock the phone for calling. The same for check-out and erasing any voice mails for the extension. The name is transferred so that should the guest call other extensions within the hotel, the hotel employees can see the name and offer the personalized response. Conversely, the phone system can also provide info back to the PMS for maid status of the room so that front desk employees can see what room are or are not available for rent. There are a number of other features (mini-bar, wake-up, DND, call block, etc.) that may also be used depending on the particular hotel PMS in use and what protocol it requires - Mitel, Opera, etc.
However, the one facet that should be there is that the phone system should be able to operate independently of the PMS. Not all hotels have a PMS system with an interface and the interface may not always be up.
They have added some codes in the dial code section that seems to deal with the wake-up function, but dialing same results in a message “You can not set wake-up now”. I am guessing that these are the initial hooks and that later firmware will provide more functionality. The PMS aspect is not really addressed other than to say who the Spanish company that developed the module is. A web search of same reveals little, but then there are few who have attempted this in Asterisk.