I have been having this issue for months now. Every time I go abroad and take my phone off airplane mode and attempt to use the mobile data in the Euro zone the following message is displayed on my screen ‘ Could not activate mobile data network’ ‘You are not subscribed to a mobile data service’. Even outside of Euro zone where I need to pay.
I have gone to the local O2 shop and customer service assistant was very helpful, looked into the issue also at this point changing my plan to Sim only. I went abroad shortly after and it seemed to be working fine. Fast forward a couple of weeks and I try to used it again abroad, same issue occurs.
I return to the O2 shop and they look into it. I have been told everything seems to be in order on their side on the system. O2 travel is active, they’ve changed the spend cap which was on 0 just in case and they couldn’t generally find anything to cause the issue.
Unfortunately, it is getting a little bit frustrating as I travel a lot with work and it has become an inconvenience. I do have an older model of IPhone, perfectly functional though. I wonder if the SIM card needs a change as it is quite old, but then again as soon as I am back in the UK, all seems to be okay, no issues whatsoever.
I am desperate for advice or any other ideas, otherwise I’m going to have to do porting of number and move to another carrier.