We have successfully tested this functionality with Vingcard, but I can tell you that I can work generically with any key vendor that supports RFID and "track2" functionality. They basically send back to OPERA the UID of the RFID card and we store it next to the reservation number.
In Simphony you can do an inquiry by "track2" reading the UID of the card and obtaining the corresponding hit.
This requires the following device to purchased and attached to the WS:
RF Ideas pcProx enroll proximity RFID reader with USB interface and dual band 125KHz/13.56MHz. (700711-355-PT)