Best data allowance - worldwide

[rfranzq]

Originally Posted by qwent1

Maybe I should work with a MVNO, or get international SIM cards but I can't figure out what is best...
If someone has a good understanding and good knowledge in this field, I would be very much interested.

There is no one magic bullet. You will probably need two or 3 different SIM cards to approach maximum benefit. The amount of money saved might be enough to hire a person to keep track of everything---get an intern!

Seriously, this is the most significant and difficult data question I have seen.
I assume most of your non-european visits are spur of the moment and almost totally unpplanned. "The plane is leaving in 90 minutes. Get to the airport and on that plane!" type of thing. Each 'unit' probably will need to understand the SIM issue and have the ability to make a wise choice.

Another issue is that it really needs to work. This would be another reason to have more than one kind of SIM. Perhaps keeping the AT&T SIMs as a backup.