Reliability Of 911 Service Via Wireless Carriers (Including VoIP)
Service for 911 is available from VOIP providers and IF the records are accurate and the service hasn't been moved, it should be as reliable as analog (regular) phone service.
There are several other things to consider though....
Cellular service is not accurate enough to trust in an emergency and you will have to tell the operator your address.
What if the cellphone battery is dead?
Analog lines were the only thing WORKING during Sandy.
If the internet goes out, you won't have 911 with VOIP. It is not uncommon to lose internet service and keep analog service (because it's battery powered). If the lines go down, yes, you're hosed either way of course.
In a real emergency 911 via a cell phone is not a good idea. You have to tell the operator your location, and be lucid and calm enough to do that. If the emergency is weather related is highly likely that the cell phone service will be down anyway...rendering that method of 911 contact unavailable.
Here's a link to an article about this exact question....
911 service is available on VoIP phones, but you, not the VoIP provider, are responsible for activating 911 service by registering the address where you will be using the ITP service. If you move the location of where you use it, you have to activate 911 service again. If you don't register your new location, the 911 feature won't work properly, and you'll risk not getting any emergency service.
Also, if you dial 911 at an unregistered address, you might end up having to pay a $75 fee.
If you lose power, you lose phone service, so your 911 service will be disabled. This will also happen if you lose your internet connection.
Generally VoIP phones do have 911 service, but it's your responsibility to register your address so that it works properly.
If you're interested, you can use the following resource tool to search and compare available VoIP phone providers, research their 911 capability, and also get free price quotes....