"Roving bug" capability is not magical. It was revealed in a court case in 2006, in a Nextel feature phone. It is probably implemented in the phone's baseband processor.
Operating a roving bug does use the phone's battery when active, of course. The tricky part is that can be activated when the phone is nominally off, probably by means of the phone waking up periodically and listening for special commands from the network.
If my surmise is correct and this feature is built into the baseband, depending on the system architecture and power management, a roving bug might use only a very small part of a smartphone's relatively large battery.
Roving bugs require secret cooperation from network operators and from chip makers (baseband firmware engineers, specifically). Makes one wonder how well these confidential cooperative agreements have held up as more chip makers are located in the PRC.
Operating a roving bug does use the phone's battery when active, of course. The tricky part is that can be activated when the phone is nominally off, probably by means of the phone waking up periodically and listening for special commands from the network.
If my surmise is correct and this feature is built into the baseband, depending on the system architecture and power management, a roving bug might use only a very small part of a smartphone's relatively large battery.
Roving bugs require secret cooperation from network operators and from chip makers (baseband firmware engineers, specifically). Makes one wonder how well these confidential cooperative agreements have held up as more chip makers are located in the PRC.