Chamberlain NDIS Wireless Indoor/Outdoor Portable Intercom Portable wireless intercom and doorbell system can be added to an existing Chamberlain intercom system for communication across your property. Crystal clear, secure 900MHz digital communication. 1,000 foot range with no wires or power connection required and battery-powered design for easy setup. Weather resistant doorbell for outdoor applications. Compatible with the following Chamberlain wireless intercoms (models NLS2, NTD2, and NLS1).