This happens when you snap a picture with your cellphone as it vibrates
billythewolf: Your phone is allowed to use any network its physically capable of using for emergency calls, whereas normally it can only use networks you’ve paid to use E.G. signals from a Verizon tower.
Mr-Magnus: There might be cellphone signal, it just might not be a signal from your phone carrier. Say you have a contract with company A, but all the cell towers around you can only connect you to company B. obviously you can’t use that signal.
However all cell phone networks, irregardless of what company they serve, must serve emergency calls by law. If your phone has any signal to any network around it it can make an emergency call, it just might not be able to make a normal call.
EDIT: I will stand by my decision to use ‘irregardless’ despite the fact that it contains a double negative and is a nonstandard word. It is a true and tested word that has been[ causing fierce debates since the late 1800s](https://books.google.com/ngrams/graph?content=irregardless&year_start=1800&year_end=2000&corpus=15&smoothing=3&share=&direct_url=t1%3B%2Cirregardless%3B%2Cc0#t1%3B%2Cirregardless%3B%2Cc1), and I am proud to honor that tradition!
^^^sorry, ^^^won’t ^^^do ^^^it ^^^again
stevenwashere: Let’s you access any cell signal available no matter the carrier. Just as an emergency service. But if there is no signal from anyone I guess it would not work. Unless somehow it can connect to a satellite.
osopolar0722: I had an emergency situation (car wreck in the middle of the night, 5m away from our tent) while backpacking in rural Chile, in the patagonia. The cell phone simply did not work.
SaucyLettuce: Emergency calls are attempted to be made no matter what, and on any network the phone can connect to. Normal calls, on the other hand, are not made this way.
CCGPV123: Do emergency calls use the same amount of bandwidth as normal calls?
paintballpmd: If I have an American cell phone and travel internationally will it work for local emergency number?
TangoMike22: Another thing that happens is that service may be limited in special circumstances. I’m not sure of all providers do this though. But in tje event of, say a natural disaster where people will be making a lot of calls they may limit service to only 911. My phone company also did this 2 occasions this summer, once when there was a major storm that cut power to the towers, so they’re operating on emergency systems, and they prematurely did it when a wildfire threatened some towers.