FIG. 1 illustrates, in a schematic diagram, an example of a device tracking system 100 architecture, in accordance with some embodiments. The system 100 includes hardware (HW) 110 and software (SW) 120 components. The hardware components 110 include an antenna 112 and a register-transfer level (RTL)-SDR device 114. The software components 120 include a GR-GSM 122 module, a scan tool 124, a user datagram protocol (UDP) server 126, a database 128 and a UDP client 130.

FIG. 2 illustrates, in a flowchart, an example of a method 200 of tracking a mobile device, in accordance with some embodiments. The method comprises broadcasting 202 an IMSI message, receiving 204 an IMSI attach request message from a mobile device, and identifying 206 the mobile device. Other steps may be added to the method 200.

In addition to the RTL-SDR 114 hardware, there is functionality to listen to Bluetooth^? Low Energy (BLE) packets (e.g., in sniff mode), which has the dual functionality of identifying “friendlies” and intruders alike. The use case presented herein includes a BLE card that can be sensed on the premises to determine if employees have entered a particular region. As will be detailed further below, this can also aid in distinguishing intruders from those who can legally enter, or have the right be on, the premises.