Question: International data roaming still happening, even with data roaming turned off in phone
I recently travelled overseas with my iPhone 5C. I am very careful about ensuring the mobile/cellular data roaming button is turned off. On return from overseas my latest account indicated I had small frequent bursts of data usage, when I knew I did not make use of data international roaming at all. Are there any circumstances in which my iPhone could access automatic international roaming for data even when this key button is disabled on the phone? In other forums I have seen several people complaining about the same issue and say it is something specific to iPhones and 4G networks. Is this just an urban myth? I have since disabled every button in the phone settings which may give it access to data when roaming, in case these somehow over ride the main "off" button. Any thoughts?
iPhone 5c, iOS 10.3.3