Wireless Commercial Intercom Systems are usually used by businesses because they don’t want the expense of running wires. Wireless intercoms also have the advantage of portability and mobility.
You can get base station units that plug into AC and communicate over the airwaves, but they can easily be unplugged and moved to another location. You can add a handheld two-way radio to this same system and people moving about the building can keep in touch with those base stations.
These systems are also built a little tougher that those intercoms found in a residence. You can add two-way radios that are built to military standards. Base station intercoms are put in metal housings for increased durability.
You can find commercial systems at intercomsonline.com.