The invention utilizes a system that links two-way communication components with inventory, fixtures, and people. Once linked, the system permits a centralized computer network to collect information about the spatial and temporal relationship between inventory, fixtures, and people using a low frequency communication protocol. When the invention is applied to a retail situation, the retailer can track inventory throughout the supply chain and can do so without substantial human involvement. Furthermore, the two-way communication components also permit the retailer to communicate directly with products on the shelves in a way that allows for re-pricing of goods or broadcasting of messages to customers, also without the need for direct human involvement.