No roaming abroad

/e/OS Devices Xiaomi
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1

Since I installed /e/OS on my Xiaomi MI 9 Lite, data roaming in other EU countries no longer works.

I can make calls from abroad but have no mobile data, even though I am logged into the partner network and the LTE symbol is active.

I have restarted the phone, switched flight mode on and off, connected different partner networks and checked the APN data.

Everything is ok.

The provider (Congstar, Germany) has assured me that roaming is active for my SIM card.

Roaming works with the SIM card in another smartphone.

Does anyone have any ideas?

I probably can’t continue using /e/OS in this state, which I think would be a great, great pity. I actually love this OS.

I once read in a post that someone flashed the baseband of the modem to solve the problem.

How would that work?

Many thanks for any tips.

Xorxus

2

it’s asking the obvious: you have “Roaming - Connect to data services when roaming” active in Settings → Network & Internet → SIMs → Provider → Roaming ?

3

Hello,
yes I have checked this button.
It is active.
But the phone behaves exactly as if the button is not active: So it is connected to the partner network abroad, LTE is active in the bar at the top and I can also make calls. The little R for roaming is visible. ONLY the mobile data is not active.
If I wanted to provoke exactly this behaviour on another phone, I would deactivate the roaming button there.
So my guess is that the button is active, but for some reason roaming is still not activated in the OS.
Any ideas?
Thanks.

4

hard to say really without A/B test of the same device, same place, same sim - with stockrom

5

I can only say that I have had the device for several years and have regularly traveled abroad with stock ROM - always without any problems.
From the day /e/OS is installed, roaming no longer works.
So it’s definitely due to a setting in the OS or a bug.
If I insert the SIM into another device, it also works. Just not in my Xiaomi MI 9 lite.

6

smartphones are highly proprietary even with a “free-er” rom on it. You can try to stockrom flash to get current OEM partitions that maybe hold a config or key neccessary for SIM auth to work when roaming, flash then /e/ again and roaming will likely work too - but it’s all speculation. If APN settings didn’t help yet I’m unsure what can without going through that process

7

I do not quite buy this conclusion, but clearly it is a bug of some sort.

I suspect that your carrier is using some Google magic to “refer” your paying usage to some other “organisation / carrier” in your “newly visited” region.

While you might reasonably expect “Europe wide” roaming … you might contact your carrier from some “newly visited” region to investigate why your apn ( ← is a link) settings “don’t quite work” here.

Perhaps also Forum Search :mag: Congstar

8

This can happen if the tower cell you are logged in does not provide data. First try to move to another area, or select another network.

Then you can try to reset your APN settings.

Settings → Network & Internet → SIMs → Provider → Access Point names → “three dots up right” → Reset default settings

Also try:

Flight mode “on”, reboot your phone, Flight mode “off”, reboot your phone again, and retry.

9

Thanks for the tips. I have already tried all that. I have been to Belgium and the Netherlands: same result.
I also reset the APN in flight mode and dialled into all available networks.
I have already tried a lot… unfortunately no success so far.
I’m going on holiday to France next weekend and will probably have to take my old LG G4 phone (with Google) with me to be able to use the SIM card in it and connect my Xiaomi to the internet via Bluetooth tethering. I don’t know what else to do. This is not a good situation at all.

Thanks.

10

can you remember the stockrom Version you had before flashing - and the version you entered with in /e/OS?

It’s a bit of work, but a stockrom reflash could be worth it. Your device had its last update up to A11 / “MIUI 12.5.3.0.RFCEUXM”, released 2022-08-20

11

Yes, stockrom Version before flashing was MIUI 12.5.3.0.RFCEUXM and version I entered with in /e/OS was e-2.9-a14-20250323478433.
I think I will reflash after my holiday as a last try.

Thanks.

12

slim chances it makes a difference if it’s the same version.

If you agree, could you adjust your title to “no data roaming abroad”, as calling and ims registration seem to work (if check confirms).

I had some basic IMS checks assembled here and here, I think you should see “registered” for IMS itself, or are those voice calls 2g/3g still?

13

I had a similar issue with my FP4 in slovenia some weeks ago. Provider is also Congstar.
APN setting was set to “Lebara”. I changed this to “Telekom Internet” (see screenwhot below), which did not help. But then I disabled the data connection and re-enabled it after a minute or so, and LTE internet worked again. So it seems just changing the APN does not try to re-establish the connection (and in slovenia the roaming was set to the wrong APN). However I do not know where the APN settings come from (SIM card or OS)

Screenshot_20250611-131343_Einstellungen
Screenshot_20250611-131343_Einstellungen1080×2340 63.7 KB

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14

yes to basic diagnostic steps, comparing APN etc. But it’s the tip of the iceberg, IMS and carrier registration can be highly device<->carrier specific. Android can show you switch buttons, but do nothing underneath (on ims things, not apn) if system services / libraries are missing or incompatible

15

There is the thought that in some cases IMS registration (if the primary issue) can only happen successfully on Stock ROM as it is speculated that this registration is written to a firmware / proprietary or other partition unused by AOSP install and likely inaccessible to /e/OS Settings.

I did not find the thread, I think an Xiaomi and @tcecyk you were involved?

Ahh … Redmi 4x - installation e/os not available? - #4 by AntonioA

16

going by this OP first description, the device has sucessful ims registration. Ofc 4636 screenshot is better, but I assumed.

The linked redmi 4x thread is different. Had mobile data, but not volte ims registration. IMS is very device / vendor specific. The carrier can let you do ims things like voice, but still decline data transport. This is what I assume for this xiaomi thread here

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