Every cell phone works by communicating with the nearby cell towers. Each cell tower’s location is known, and each cell phone has a unique identifier. It’s simple to calculate geographic location from which cell towers are nearest and at what distance. And of course each call is well known to the system. Not only this but the concept of “switched off” is fictional to an important degree — it’s possible for phone software and hardware to be active even when it’s off. And it is definitely possible to compromise phones and install software on them without users’ consent or knowledge. And that can include access to microphone and camera. My understanding is that everything I have written here is true of button phones as well as smartphones.
Every cell phone works by communicating with the nearby cell towers. Each cell tower’s location is known, and each cell phone has a unique identifier. It’s simple to calculate geographic location from which cell towers are nearest and at what distance. And of course each call is well known to the system. Not only this but the concept of “switched off” is fictional to an important degree — it’s possible for phone software and hardware to be active even when it’s off. And it is definitely possible to compromise phones and install software on them without users’ consent or knowledge. And that can include access to microphone and camera. My understanding is that everything I have written here is true of button phones as well as smartphones.
Further, tower sites have "panels" (antenna), they cover about 120 degrees. It is known what panel a phone is connected through/with.
Signal strength and math can develop an arc of probable location in that 120 degrees.
So if a connection to a tower is used, the more crowded the better, but then there are Ring cameras and such.