This was with an Android, but how else does it guesstimate your location? I assumed via IP
Much location detection uses WiFi mac addresses sucked up by stuff like street view cars. Uses much less power. Google have an API to look up a set (min 4) of mac addresses and tell you where you are.
I built a tracker with an esp and two AA batteries. Worked like a dream.
That's using WiFi access points, not devices like phones.