A business consultant I knew through a past job was involved in the creation of a sort of competitor - basically they were FM radios with no tuning dial, it was just fixed on one station's frequency and they had an internal speaker as well as a line out to connect to the business phone or PA system - in those days, before the fancy PBX systems were common, you had a standard PA system tied to a specific phone extension (or multiples - so you could page just specific areas) and you dialed an extension which connected you to the PA input. Not as common any more as PBX and IP phones usually have an internal intercom feature for paging.