sentences:  Hotel property management systems may have integrated or interface with third-party solutions like central reservation systems and revenue or yield management systems, online booking engine, back office, point of sale, door-locking, housekeeping optimization, pay-TV, energy management, payment card authorization and channel management systems.With the advancement of cloud computing property management systems for hotels expand their functionality towards new service areas like guest-facing features.These include online check-in, room service, in-room controls, guest-staff communication, virtual concierge and more.