As the number of Access Points and stations sharing the unlicensed ISM (Industrial Scientific Medical) bands increases, interference diminishes the theoretical performance of 802.11 standard. This paper presents results of the performance of an IEEE 802.11b/g network in a public facility infrastructure which needed to deploy more than a thousand access points to provide an IIoT (Industrial Internet of the Things) item location service. As a first step to better analyze such network characteristics, this work studies the channel occupancy, the RSSI (Received Signal Strength Indicator) variation and the throughput of a static and mobile station. The study also analyzes the performance of Voice over IP over the wireless network. The results reveal the inefficient use of the wireless medium in a large 802.11 network due to multiple radio propagation conditions.