US Phones Will Report Vertical Location to 911 Dispatchers by 2021

The FCC has officially adopted new rules for the accuracy of
location data reported to dispatchers when someone dials 911 on a
cell phone in the US. For the first time, vertical position data
will be required, so first responders can quickly locate people
needing help in multi-story buildings. The rules will be phased in
starting April 2021. Vertical position will need to be accurate to
within 3 meters for at least 80% of indoor 911 calls. The rules
also impose new requirements on standard location data sent to
dispatchers by wireless carriers, such as a dispatch-able street
address and apartment number.

Source: FS – Phones
US Phones Will Report Vertical Location to 911 Dispatchers by 2021