My wife and I have received a bill, albeit small, for a few Mb’s for roaming in Dubai, yet our data was switched off from the moment we left UK until we returned? We know our phones so not tech biffs! Anyone else had this? We are new to O2 so tbh feeling suspicious of them at the moment.
Some apps will connect / send sms whilst roaming, even if data is switched off.... As you give them permission to use the phone.
It could also be things like WiFi Assist, connecting if a drop in Wifi is detected.
Hmm the system can use data for things like APN updater which I guess could be happening when roaming even if roaming is turned off since the device may need to configure itself for better connectivity.
Also some other system apps particularly if related to security, like carrier services often can override in the same way APN updater can.
I'm curious though if this is an Android system, was roaming also disabled aswell as network data?