Mobile carriers can get your GPS location

This has been the case since the e911 project in the 1990's and is mandatory. Prior to this I would reset the message waiting indicator on their phone continuously to see what cells and cell sectors they were moving through but that would basically just show what road or roads they may be on and what direction they are going very roughly. Assisting the FBI with tracking kidnappers or at least that is what they told me.

There are loads of other tags that can be set on someones phone. My favorites were priority override and caller-id blocking override. This was before SS7 spoofing was so prevalent.