The Telex BTR-700 is a professional UHF wireless intercom Base Station, offering full-duplex, frequency-agile support of up to 4 beltpacks plus a headset section for simultaneous five-person intercom communication, rugged all-metal construction, and a huge set of user selectable frequencies arranged in 24 factory preset groups.
 
https://www.bhphotovideo.com/c/product/334952-REG/Telex_71303B4R5_BTR_700_Single_Channel.html