How are 911 calls made on a cell phone or VoIP routed?
We now live in SC, but both my husband and I have TN cell phone numbers, and our house line is also a TN number since it’s VoIP (we run servers out of TN). If I woke up to my house on fire and called 911, how much delay would there be in getting the right dispatch? Would it be more prudent to have the house line a local number, or to get a local cheapie cell phone?
File under ‘thoughts keeping me from going to sleep tonight’…
Don’t know about SC, But in Calif the cell phone tower routes all 911 calls to a local agency. In Northern California at one time a 911 calls went to Vallejo CHP. And they answer something like 911 what is your emergency. Then they route the call to the proper department.
Most GPS enabled phones can send that information to the dispatcher. Also the street address listed for a land line is sent, maybe the same is true for VoIP accounts.
VoIP depends on the provider; it would be best to actually contact them and ask. They might have it registered to a TN location, or they might not support it at all.
In my area 911 calls, regardless of where you are, go to the Milwaukee County Sheriff’s Department (or maybe the Milwaukee County Police Department). The first thing I usually say is “Can you transfer me to [city I’m currently in]”. About half the time they just transfer me over to the 911 dispatcher at the city I asked them for and the other half of the time, even after asking them a few times they still make me tell them what’s going on and then say “Oh, I’ll have to transfer you to [city] for that” (no kidding).
At my work I have all my managers keep the local PD’s non-emergency number in their cell phone. The 911 dispatcher answers the non-emergency line as well and I’ve taught them that if there’s an emergency (and they’re thinking clearly) it’s faster to just use that number than to dial 911 from a cell phone. Technically, it’s faster to use the landline and dial 911, but sometimes you’re not near a phone.
Supervisor at a 9-1-1 center chiming in here…
Cell phone calls to 9-1-1 are routed to the Public Safety Answering Point (PSAP) nearest the caller without regard to the home address on the account. (Your cell phone is an account in TN. You dial 9-1-1 in SC. Call is answered in SC) But there are a couple of minor caveats that might come into play with cell phone calls to 9-1-1:
Calls using a VOIP phone will most probably be routed to the ten digit phone number of the PSAP that covers the physical address where the account is registered. If your PSAP account is registered in TN but you live in SC, then your 9-1-1 call would most likely be answered in TN. The call taker can try to assist you to transfer your call to the correct PSAP but this is a much slower process if it is not a neighboring jurisdiction that the call taker is accustomer to.
My suggestion is that you contact your local PSAP on a non-emergency line and inquire what the proper ten digit number is that you can dial to feed your call into the correct local PSAP. You can then program that as a contact for your VOIP line. You would just need to select your contact rather than dial 9-1-1 if you use your VOIP line.
Good stuff!!
interesting question by the OP, and it makes me wonder - about 99% of the time, I don’t have “Location Access” enabled on my phone - does that ever play into the original question at all?
Iggy, Thank You! That is exactly what I was looking for. My google attempts gave “make sure to identify your location and do call back…” info, but nothing beyond the most basic of tips.
I also restrict GPS access on my cell phone more often than not, so I think finding the correct number to have on file is a good idea, as well as programming it into the house phone. We don’t use it much, but it’s come in handy a time or two so we hang onto it.
Thanks all for your input - I knew this place would get me an answer! 
For my VoIP service, e911 service is an optional add-on. For $1.50 a month they will suitably route your call to the nearest 911 center and you caller-id and address will show on that center’s screen. No fee, no 911.
They make a big deal about how they aren’t taking this money, it’s just being relayed to another service that is charging so much money.
If you opt-out, you either have to have a cellphone or dial the local emergency 10-digit number (and convince them not to tell you to hang up and dial 911).
I’ve used a cell to call 911, in particular when my son was 4, and had a croup attack, and was having trouble breathing. The ambulance got here in about 3 minutes.
While I’m telling the story, I’m going to plug one of my causes-- call an ambulance, don’t try to drive to the hospital yourself. The EMT got our son on oxygen immediately after arriving, and his pulse ox went from 78% to 97% in about 2 seconds. Then he gave him inhaled steroids, which made him breath easier, so he stopped panicking and crying, which was complicating the situation. The EMTs took care of him for about ten minutes in the ambulance before transporting him, and probably saved his life.
If we’d tried to drive him there, he would have been in the back of our car, sucking air and crying, with his pulse ox low, and maybe getting lower, for the 15 minutes that it would take us to drive to the hospital, and then as soon as we got there, we’d have to find emergency, take him in, explain to someone, and they’d have to mobilize.
I think my son is alive-- and not brain-damaged-- because we called 911 instead of driving to the hospital ourselves.
If your PSAP is capable of receiving phase I or phase II location information they will get it regardless of phone settings. Some data is dependent on GPS data from the phone (phase II). If your phone doesn’t have GPS capability then obviously it will not get transmitted to the PSAP. Less precise is phase I data, basically triangulating between the various cell towers that hear your call. since that is not handset dependent, the PSAP should get that data if the PSAP is set up to handle it. Not all PSAPs are.
Same goes for *67 blocking the outgoing caller-ID… it will not block that information from going out to 9-1-1.
But, if you call a ten digit number to reach the PSAP then we don’t get any of that data. maybe only get caller-id like you get at home, with the same limitations.
As far as I understand, VOIP routing to 9-1-1 is based upon identifying your IP address. If your VOIP connects through a VPN then they likely could not route your 9-1-1 call correctly. Won’t apply to all or even most, but it could be an issue for a few.
On most phones, the ‘location data’ setting only applies to third party services. Sending your location when you call 911 is NOT optional (carriers are required by law to provide that information) and cannot be disabled. Read the section in your users manual (usually easiest to find on the carriers website) about location data and it will explain specifically what location data you’re allowing to whom with each setting.