An interface gateway facilitates communication between a first device and a second device serving a hospitality establishment. The first device is one of a property management system (PMS) and a guest service device, and the second device is the other of the property management system (PMS) and the guest service device. One or more communication ports perform data communications with the first device and the second device. One or more processors receive a message from the first device, determine that the message is in a first format, determine that the message is applicable to the second device, determine that the second device supports a second format, convert the message to the second format, store the message in a transmit queue with an indication of whether a confirmation reply is expected from the second device, and send the message in the second format to the second device.