725 ILCS 137/5
As used in this Act:
"Cell site simulator device" means a device that transmits or receives radio waves to or from a communications device that can be used to intercept, collect, access, transfer, or forward the data transmitted or received by the communications device, or stored on the communications device, including an international mobile subscriber identity (IMSI) catcher or other cell phone or telephone surveillance or eavesdropping device that mimics a cellular base station and transmits radio waves that cause cell phones or other communications devices in the area to transmit or receive radio waves, electronic data, location data, information used to calculate location, identifying information, communications content, or metadata, or otherwise obtains this information through passive means, such as through the use of a digital analyzer or other passive interception device. "Cell site simulator device" does not include any device used or installed by an electric utility solely to the extent the device is used by that utility to measure electrical usage, to provide services to customers, or to operate the electric grid.
"Communications device" means any electronic device that transmits signs, signals, writings, images, sounds, or data in whole or in part by a wire, radio, electromagnetic, photoelectric, or photo-optical system.
"Law enforcement agency" means any agency of this State or a political subdivision of this State which is vested by law with the duty to maintain public order and to enforce criminal laws.
725 ILCS 137/5