A wireless communications system (20) includes a wireless communications network (35) and a plurality of wireless communications devices 21, 36). The wireless communications devices are each configured to communicate via the wireless communications network. At least one of the plurality of wireless communications devices has a portable housing (31), a wireless transceiver (24) carried by the portable housing, and a wireless-based, availability detector (29) carried by the portable housing. A processor (22) is carried by the portable housing and is configured to determine a first availability status based upon the NFC device (25) at a first time. The processor is further configured to activate the wireless-based, availability detector based upon the NFC device to thereby determine a second availability status based upon the wireless-based, availability detector at a second time after the first time. The processor is additionally configured to communicate the first and second availability status to the wireless communications network via the wireless transceiver.