[dataway]

Airtags only have bluetooth range but they will ping any nearby phone, even if that phone has no interest in the tag ... the location then goes into the Apple system and the Tag owner can retrieve the location. That how you can put one in a garbage bag and track it around the world ... any Apple device within blue tooth range will pick it up and report the location to Apple.

Beeping a local unknown Airtag was recently added to help people determine if their car or whatever has a planted Airtag.

Also a ton of more profession cell system, gps trackers that can report a location via the cell phone network back to the trackers owner.