or “building allow/disallow lists of mobile country codes (mcc) for data roaming”
if you pass Switzerland or you’re close to its borders and you’re spoiled by the roaming regulation in the EU, there’s no automatic way to exclude data traffic per country and turning it off and on again when leaving the EU or when returning.
The apns-conf.xml has the MCC code per carrier already to build an exclusion list upon per country. But there’s no code in Android yet to do this. There are helpers though that warn when connected to a country not on an allow list.
- https://play.google.com/store/apps/details?id=dk.quan.roamingguard
- https://play.google.com/store/apps/details?id=com.martindoudera.euroaming
Up to Android 4.4 apps had a permission to disable the data connection when connected to a non approved mcc - since Android 5.0 it’s down to a notification.
The most recent and voted up issue on EU-only data roaming at Google is #110842017