Hanging up will send your info to them and they will call back to make sure there isn’t an emergency.

911 dispatcher here

This will depend a bit on agency policies and technological capabilities as well as what emergency info you’ve filled out on your phone and unable to be shared in an emergency call

At my agency we get a lot of butt dials, our policy for hang ups or open line calls from a cell phone is that as long as we didn’t hear anything suspicious (someone yelling, gunshots, etc) we will usually disregard the call. If we have an open line we’ll listen for about 30 seconds or so and if nothing sounds off we’ll disconnect and continue about our day. If something sounds fishy we’ll stay on the line/call back, and we’ll send police to the area if we have a good location.

There’s a couple exceptions, like certain wifi calling or femtocell setups are treated as being from a landline because we have a solid address, so we’ll always dispatch police unless you stay on the line and confirm that there’s no emergency.

And our discretion comes into play a bit. We might ignore 1 or 2 hang ups from the same number, especially since the calls may not even ring through to the same calltaker so it may not be obvious we’ve gotten multiple calls until we’ve gotten a good handful.

Different agencies policies on that will vary. I know one of our neighboring counties will always send police to the area when they get a hang up whether or not they heard something suspicious.

And as for the information that’s shared, by default all we get is your phone number, carrier, which cell tower it hit off of, and an approximate location based on cell tower triangulation (which is kind of hit or miss, sometimes it’s really accurate, other times it’s basically useless)

If we need to we can contact the phone provider to try to get subscriber info. That can take a while and can be hit or miss too, like if you haven’t updated all your information with them, if you’re on a family plan with other people, or if you’re using a smaller provider that is really just reselling Verizon/T-Mobile/AT&T service, it can make it a little hard to accurately track down who actually owns that phone.

If you’ve called recently, we can try to look up your information from priors on your phone number.

If you’ve filled out your emergency/sos info, and enabled it to be shared with us, we can access that, It also often gives us access to a more accurate location for you, but otherwise we only get what you’ve put in there. If you haven’t kept your name, address, emergency contacts, medical info, etc. accurate and up to date there, that’s another stumbling block for us. We can sometimes work backwards from what info is there, if we have your name and age we can try to narrow things down, but if you have a common name it can be hard to tell which 27 year old John Smith is the one who called us.

Do with that what you will, fill out your emergency info or don’t depending on what you’re comfortable sharing with us, consider how it might be used to save your life if you’re, for example, in a car crash and too hurt to speak to us, or how an oppressive government might use it to track you down at a protest (from 911 we can’t just access data on random people’s phones unless they call us, and we can only request a ping on a phone number from your phone company under certain circumstances, and that’s a bit of a process and all it returns is your location based on cell tower triangulation, which again isn’t always very accurate. Police and certainly the feds have a bit more leeway than we do, though I don’t know the extent of that, and if they set up a stingray or similar device I have absolutely no idea what they might be able to access)