> There's tons of trackers that can use any nearby iPhone If you're limiting the conversation to "any iPhone" then there's a few, such as the Chipolo One, whic

> There's tons of trackers that can use any nearby iPhone If you're limiting the conversation to "any iPhone" then there's a few, such as the Chipolo One, which also use Apple's network. However, Samsung has a competing network which uses any nearby Samsung phone (also a popular brand, so I'm told) and Tile has a network which uses any phone that has the Tile app installed. None of these need GPS to work, though their networks will probably be smaller than Apple's in most US cities.