Hello . Thanks for your reply. What do FDD and TDD mean?
thanks
Anne Marie

Hi,
We want to buy a M7350 MiFi Router in Belgium (Coolblue) to use it in Spain and buy a local SIM card there. And then use the WiFi connection with our cellphone (belgium sim card) or tablet.
Will this work ? How can or can´t I be sure ?

What does FDD and TDD mean ?
Thank you for your help

FDD and TDD are both network types/standards for 4G. The SIM card and the mifi product have to support the same standard to work with each other.

That's not recommended because the device from Belgium may have compatibility issue with the SIM card from Spain. It is safer to get a device in Spain and use it with Spain SIM.
For the compatibility part, you can check the network type and frequency of the SIM in Spain and compare it with the network type and frequency supported by M7350 in Belgium: http://www.tp-link.com/nl-be/products/details/cat-14_M7350.html#specifications
But the tricky part is that even the network type and frequency matches, we cannot make sure they will work with each other because the internet service provider may have special restrictions that we don't know.

Also you can check whether your SIM card support data roaming in France and Spain, and if the SIM card do support roaming, check the APN settings on the M7350 to see whether it matches the settings of local internet service provider in France and Spain.