A wireless intercom is a telecommunications device that enables voice communication without the need to run copper wires between intercom stations. A wired intercom system may incorporate wireless elements.
There are many types of wireless intercom systems on the market. Most wireless intercom systems communicate by radio waves using one of the frequencies allotted by various government agencies. There are also systems that advertise themselves as wireless, but communicate over existing building AC electrical wiring.
Read more about Wireless Intercom: Basic Terms, Wired Vs. Wireless, U.S. & Canada Wireless Frequencies, Systems That Use Existing Electrical Cabling