Tips for calling 911 with a cell phone

Share your tips for safe hiking, surviving in the wild and managing hiking injuries!
Post Reply
Joseph Elfelt
Posts: 157
Joined: September 3rd, 2010, 10:24 am

Tips for calling 911 with a cell phone

Post by Joseph Elfelt » December 19th, 2016, 3:10 pm

Earlier this year I became interested in what happens when someone with a cell phone calls 911. In particular I wanted to know the details of how the 911 dispatcher learns the *location* of the caller. What kind of digital magic happens behind the scenes?

On one hand I learned that the FCC requires a wireless carrier handling a 911 call to produce coordinates for the caller’s location. Sounds good, right? On the other hand I learned that many carriers have exempted themselves from this requirement over large portions of the area they serve. I also learned that the coordinate accuracy most of us easily get on our smartphones is often 10 times more accurate - or more - than the coordinates produced by the wireless carrier handling a 911 call.

Early on as I dug into this topic it became apparent to me that everyone needs an app on their phone that will be easy to use in an emergency and will display their coordinates in the proper format and the accuracy value for those coordinates. That realization led me to develop FindMeSAR (

Today I finished a report that shares what I learned. That report consists of:
1. A list of tips for calling 911 with a cell phone.
2. Background information so you understand the big picture.
3. Detailed information to support each tip.
For those wishing to dig into the source material for themselves, the report includes links to various documents on the FCC website.

If you find this report to be useful I hope you will share it with others.

Report: ... -phone.pdf

Posts: 19
Joined: September 5th, 2016, 9:24 am
Location: The Netherlands

Re: Tips for calling 911 with a cell phone

Post by dikkeknodel » February 21st, 2017, 5:11 pm

Nice one! Thank you for paying forward.

I hope I never need it!
Keep hiking!

Post Reply