iPhone 12 ProMax No Service issue after 14.5, stil happens in 14.6

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iPhone 12 ProMax No Service issue after 14.5, stil happens in 14.6

I have an iPhone 12 ProMax, I use DualSIM with T-Mobile/AT&T.. Ever since 14.5 (when Standalone 5G was enabled).. if I leave the phone in airplane mode for an extended amount of time (I work for an airline, and do this for a few hours.. 1-4 times a day when working), when I take it out of airplane mode.. it will say "No Service" until I reboot the phone.

I've Tried:

1) DFU software re-load through my mac, thinking an upgrade did not go as expected..

2) removing the AT&T SIM and doing single SIM service (T-Mobile is primary).

3) Moving the T-Mobile service to a physical SIM for a week (it's back on eSIM now).. still the same result.

4) Resetting Network Settings

I'm not sure what to do, as this iPhone 12 is absolutely the worst iPhone I've had as far as network connectivity. I've got a 2020 iPhone SE we keep around the house in case someone breaks the phone.. with the same T-Mobile or AT&T SIM cards.. it does not have the "No Service" problem.

I'm not eager to take it to the apple store, as i'm sure it'll function fine when there.. but needing to reboot my phone every time we land and i've got some sit time.. or just want to quickly check if I have messages is quite annoying, this week i'm carrying the iPhone SE with my SIM in it because it at least "works" but this screen size is horrible after getting used to a 12 ProMax.

Any suggestions on how to actually fix this? As i'm sure it's more of a baseband/software issue that came along with SA 5G being enabled.

Posted on Jul 10, 2021 3:26 PM

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Answer 1

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bradcr162 Author

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Jul 10, 2021 5:48 PM in response to lobsterghost1

Right, did you read the important information in the OP post as to *when* it's happening? I'm going to say no based on your reply.

It's not when i'm in "regular" use.. it's when i'm working and have to go into Airplane Mode for extended periods of time, the modem just simply fails to fully look for service and settles on "No Service" until the phone is rebooted, then service restores fine.

I'm really just trying to see if anyone else is noticing this, but it's a niche situation as most people do not fly nearly as often as I do.. so i'm betting you likely do not have to use Airplane mode like I do either.. thus not experiencing this issue ;)

I just included the SIM swaps as a troubleshooting step I had completed.. I actually have far more issues with my AT&T SIM as far as slow data and indoor service dropping to 4G/HSPA than I do on T-Mobile... Thus why I do not use AT&T as my main carrier... but I am from a market AT&T is notoriously bad, but they help fill in gaps when i'm in rural areas... so I keep the SIM as it's a cheap backup.

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Answer 2

bradcr162 Author

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Jul 10, 2021 5:02 PM in response to lobsterghost1

That's actually what I've had it set to (well currently LTE, as T-Mobile is working on the n41 panel by this hotel, so it's... T-Maybe on 5G currently)

I usually only do 5G On in a spot I know it's n41 and I do not want it handing down to LTE to save battery.

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Answer 3

bradcr162 Author

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Jul 10, 2021 5:33 PM in response to lobsterghost1

I would agree with you.. but the AT&T SIM also shows "No Service" as well in the same situations.

This does not happen on my Samsung Z Fold 2 5G with T-Mobile, the iPhone SE on T-Mobile.. just the 12 ProMax.. so this is clearly an iPhone 12 issue after apple bungled the SA-enabling update in the baseband, as I had ZERO issues until the 14.5 update.

The issue tonight with me needing to use LTE in this particular location is due to integration/antenna upgrades on a site across the street from the Hotel i'm currently in for work - I've been through network integrations with AT&T, Verizon, and T-Mobile at this point and that's normal behavior.

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Answer 4

bradcr162 Author

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Jul 10, 2021 5:53 PM in response to lobsterghost1

Well, I have the issue on AT&T as well.. but AT&T is because when I go inside buildings around my neighborhood they simply do not work deep in buildings (which is odd, as I live in Chicago) I often see "AT&T Using Cellular Data" when inside places like target, grocery store, or high rises around my specific neighborhood as it has to use T-Mobile to make an IP connection back to AT&T.

Again, this does not happen on the iPhone SE on the account, the Samsung Galaxy Fold 2, OnePlus 8, iPhone Xs Max on the other person's line.. just this iPhone 12, and did not start until apple enabled the SA update.

It could be they screwed something up with the dual-sim support as well when enabling 5G support for the dual-sim... I just am feeling around if it's worth fighting with apple about at this point.. or just dumping it on Swappa whilst it still has value.

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