https://www.theregister.co.uk/2018/02/20/vodafone_4g_drone_tracking_idea/

Vodafone is working on an airborne drone detection system based on 4G M2M mobile phone technology, the network operator said this morning.

The “pioneering technology”, as Voda has dubbed it, works by putting a standard 4G SIM card and radio onto a drone. The mobile operator then tracks the drone through a method that it calls a Radio Positioning System (RPS, capital letters and all).