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Use Emergency SOS on your iPhone

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Question: Does the location portion of SOS work without active cell service?

My wife is a stay at home mother of a newborn and rarely leaves the house. She uses our home wifi with Google voice to make and receive calls on her iPhone. (Why pay for cell service if you don't need to?)

If she is not connected to wifi I know that she can still make 911 calls (in the US). But the SOS also sends text messages with location information. Without service are these treated the same as 911 calls and accepted by the carrier regardless of service?

iPhone 6s Plus

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Dec 14, 2017 8:55 AM in response to VT-CountryNerd In response to VT-CountryNerd

When you say without service, do you mean she just does not have an cellular telephone service set up with a carrier, or there is no cellular signal where she is? In the USA, all carriers must support and allow 911 calls on their cellular networks even if the handset has no associated carrier or service established. So as long as she has a cellular tower within range, then yes, the SOS feature 911 call should go through (oh, and of course, make sure she does not have airplane mode on and just wifi enabled).


Without cellular telephone voice service with SMS enabled on the account with the carrier, she cannot send texts at all. Her iPhone would be restircted to iMessage only, which of course is an internet messaging service and only works between Apple devices.


SMS messaging is only possible if you have an SMS messaging plan and service with a cellular telephone service provider. SMS texts are sent over the cellular telephone voice channel, and do not use either cellular data or any internet connection at all. MMS uses cellular voice bandwidth for the text portion, and cellular data for the data portion.


Even though Google Voice has an instant messaging service with it, that is not a native SMS service and is handled by Google's hardware, so the SOS function and the iOS messaging app cannot send or receive Google Voice texts.


So, bottom line is that without cellular service, the 911 call part of SOS should work as long as the device is within range of a cellular telephone tower. But without cellular service, the SOS texting function won't work at all.


Use Emergency SOS on your iPhone - Apple Support

Dec 14, 2017 8:55 AM

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Dec 14, 2017 10:16 AM in response to Michael Black In response to Michael Black

No, I do not mean no cellular signal. I do realize that without a signal of any kind the no communication is possible. What I meant is that her phone does not have any sort of carrier service set up. (I though that was clear in my post)


I knew carriers were required to support 911 calls. I assumed that there is no SMS support required, I just wanted to make sure that there hasn't been a change with all of the SOS updates that now required carriers to support them.


And I did not figure Google's service would work, as it works using a data connection on the user end and without a cellular service plan, the user would not have a data plan.


For a follow up question: If no SMS or iMessage is available, what is done with the data collected? Is it stored to be transmitted when a connection can be established, or is it discarded?

Dec 14, 2017 10:16 AM

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Dec 14, 2017 10:29 AM in response to VT-CountryNerd In response to VT-CountryNerd

I am not sure what you mean by data collected? The SOS feature in your scenario is going to place the voice call to the 911 call center, and will use the e911 cellular system to approximate location and send that info to the 911 call center (e911 on an iphone uses location services, so aGPS if possible, cellular radio tower location info, etc - whatever location services on the handset can get data from).


If there is no way to transmit the SOS texts/contacts you have set up, I don't believe anything is cached or saved at all. The send simply fails and that's it.


You might want to look into an inexpensive pre-paid service that includes SMS texting so at least her SOS activation would send texts to key people you'd want notified of the emergency. Try to find a pre-paid option with minimual calling minutes and even a limit on SMS texts would be okay in that situation, as you'd only use them up in the event of an actual emergency.


She could still just stick to the GV app for calling, and in message settings, dis-able the send as SMS option. That option only applies to iMessage contacts who cannot be contacted via iMessage at the time an iMessage send is attempted. It does not disable SMS texting to non-Apple devices.


With a pre-paid service, she'd also have backup communication in the event your wifi or ISP has an outage.

Dec 14, 2017 10:29 AM

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Question: Does the location portion of SOS work without active cell service?