The VTech VC7002 Open/Closed Sensor is an accessory sensor only. It requires a VTech VC71000 IP Hub a VTech ULE Certified Baby Monitor or a VTech VC7151 Wireless Monitoring System with Cordless Telephone to operate. With the VC7002 Open/Closed Sensor youft. ll know if anything you care about like a window door or medicine cabinet is open or closed for peace of mind at home.