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Comment by oceliker | Hacker News Reader

This is so odd. I have two phones with AT&T currently sitting right next to each other. One has service, the other is in SOS mode.

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Some of our staff are reporting similar where their partner's phone has service and their's doesn't. Both on same AT&T family plan.

So the radio bands may play into it although I would think with latest iPhones, they can use any of the bands from AT&T although I could be wrong.

I'm on the latest iPhone and it's SOS for me

I'm wondering if it could be some kind of auth timeout. I've heard from a few people of one person's phone going out, then a bit later the other person's phone finally failing too.

Yep: my partner's iPhone has service while my Pixel doesn't, both on same plan.

Can you check if things improve if you turn off 5G and move to 4G/LTE instead?

Good thought, but switching to LTE only didn't work. Same result of ending up in SOS only. Cellular over wifi works perfectly fine though. Wish we could count on better post mortems from the phone companies, but I'm not holding my breath for it.

There are some reports that phones with e-sims are less likely to be impacted versus phones with hardware sims.

I have eSIM only (iPhone 15) and was impacted the same as physical SIM users on AT&T (Boston area).

I suppose I can't speak to likelihood with a sample size of one.

Does it still show bars in SOS mode? Or is SOS just “I dunno can’t see no cell towers but maybe it’d work?”

I wonder if the MVNOs that piggyback on AT&T are showing down also. If not, it’s some AT&T service authorization system that exploded.

Mine says SOS Only, shows no bars.

SOS mode means it can see towers of other providers you aren’t authenticated with, but no signal to authenticated cell towers

On the latest iPhones, SOS mode is the emergency fallback to satellite service. It's really meant to be used in situations where you're well outside of any sort of service area but you have a clear, unobstructed view of the sky.

Your iPhone will instruct you on where to point and help you track an emergency satellite that is manned by live humans who will take your emergency request and relay it to the proper people.

More specific info here: https://support.apple.com/en-us/104992

Won't that only activate if it can't see or communicate with any towers at all?

I’m pretty sure that “SOS only” can also mean the phone seeing networks it can’t register with but which it could make an emergency call on if required. This predates satellite SOS.

SOS means it has cell service and you can call 911.

If there is no cell service then it's SOS with a little picture of a satellite next to it.

Except SFFD is reporting that (some) AT&T customers are unable to call 911.

SOS mode typically means that your phone is connected to a carrier other than one you have a contract with.

I wonder if some devices bungle their failover. The exact failure mode state of AT&Ts network might cause some devices to hang onto AT&T’s RF.

Not sure why the downvotes but this is cool I wasn’t aware of this technology, thanks!

Emergency only means 911 calls through whatever provider is available.

Same here. Strange. Would love to know the reason!

My wife and I were riding in the car next to each other. Took mine about 5 to 10 minutes longer to jump to SOS mode.

I wonder how SIM registration works? For example if it's like a token with an expiry. If some set of registration servers on the network couldn't renew then I could see behavior like this.

Different bands could be affected differently if it is solar radiation related. Same exact model of phone?

Different models, in my case.

Same year, different size (13 and 13 Pro Plus)

Ditto, mine and my wife's. In my case, the working one is slightly newer (15 Pro Max vs 14 Pro)

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