Roaming stopped working all of a sudden

iioonnee

Hello,

I used to be able to roam in the UK on my Samsung Galaxy A12 which connected to Telefonica (O2) for the longest time. My home network is MTN Nigeria. On putting my SIM into a Google Pixel 9 after flashing GrapheneOS, I had no cell service and saw “emergency calls only” by the signal bar. When I put this SIM back into my old phone, it too now no longer receives any service. When I manually select O2 network in settings, I get an error that the service is unavailable. Same when I select the other roaming partners of my home network. Of course I also have roaming enabled in settings.

I know it's not the phone because I have e-sim working on one network alongside nano SIM of another. Customer care of my home country repeatedly informs me that I am successfully roaming. They ask me to restart the phone, try another phone etc, but these things are of little help since I knew to do those already.

I would like to take further steps and collect technical information to suggest informed action points when I visit O2 office in UK or when next I contact MTN Nigeria

What diagnostics info can I collect to understand the exact reason (from the phone's perspective) why I'm unable to roam? I develop software for routers, but have next to nothing understanding of cellular networks.

Please help.

Thanks

iioonnee

iioonnee Got in touch with better support. Phone was choosing the wrong roaming partner. Required manual selection at least once. SMS not yet working. Will update when shortly

de0u

iioonnee Thanks for reporting back!

Johnnyloans

iioonnee

If SMS is the only issue now, try another app like fossify messages or google messages?

The latter might have better compatibility worldwide.

Fossify:
https://github.com/FossifyOrg/Messages

iioonnee

Support (customer care of my home network. I am roaming) has done all the necessary provisioning on my line. They asked me to test in another phone. I could make calls and send/receive SMS when I moved my nano SIM to my old phone: Samsung Galaxy A12. The conclusion after all the back and forth with support was to contact the device manufacturer or retailer because they had verified everything was good on their end.

I didn't tell them I was using GrapheneOS though.

In the SMS app logs, I see

MessagingApp: SmsSender: failure in sending message part. requestId=content://sms/28 partId=0 resultCode=112 errorCode=111

Pretty much stuck now. I am on build number 2026040300 and using Pixel 9.

Getting itchy know Android enough to investigate these system issues and contribute

@GrapheneOS

de0u

iioonnee The conclusion after all the back and forth with support was to contact the device manufacturer or retailer because they had verified everything was good on their end.

Roaming is complicated. From the information at the beginning of the thread it sounds as if there were some inter-carrier issues. Perhaps such an issue has been fixed, but perhaps there are more of them. Since the device is running something newer than 2026020600, has cross-SIM calling been tried?

iioonnee

Yes, I have turned on cross-SIM and it appeared to make no difference. Sigh.

Thank you for the suggestions though.

Johnnyloans

iioonnee

Try these 2 things:

Settings > system > reset > reset mobile

Settings > network > SIMs > [tap on your SIM] > Access Point Names
Confirm with your carrier that the information here is correct.

iioonnee

Johnnyloans I had previously gone through reset and verified the APN settings from their website and other sources. Since the preferred roaming partner changed without notice and they had to reprovision my line, I have requested details of their APN settings just in case that changed without notice too.

After the above, I'm not sure what else to try, but I will keep this thread up-to-date for one random helpless bloke.

I looked at the messaging app source code, but it's mostly Kotlin Android which I don’t yet speak. My last resort would be to investigate this myself. It'll be a shame if it has to get to this, but it is what it is. At least it's not proprietary.

Sigh

iioonnee

Johnnyloans Naaaa...been there done that, though I'm only trying Fossify now. It tells me immediately that the message was not sent because “service unavailable”. The original messenger app tells me the message was not sent.

Support has escalated the issue. The assumption has been that I'm running Google's Android, but I'm gonna have to break the news at some point.

iioonnee

This issue has now been resolved. Customer care sent me yet another message their their preferred roaming partner has changed and that I should select EE or Vodafone network manually. I was unable to connect to Vodafone, but EE worked.

From O2 to Three to EE all within the space of a few days. Oh well, it ended well.

Thank you all for the help.

de0u

iioonnee Thanks for reporting back!