What are the problems related to roaming?

Cost and performance
In case of roaming, your home phone operator pays the Italian operator according to their specific agreement, usually fees starting from from 10 up to 500 €/Gb (for extra UE roaming).

Consequently, if you use roaming “by consumption”, in the best scenario, you may pay up to double the fees stated above...

Instead, if you use roaming in a “pre-paid package”, you will be able to have traffic up to an extremely limited amount, and if you surpass it, depending on the operator, you can purchase another package, or continue to navigate at an extremely limited speed (generally 128Kbps), or pay by consumption.

Settings
Roaming is usually with only one specific operator (depending on your operator agreement with the italian operators) , so if you do not set your device to the correct operator or incorrectly configure the device, you risk very higher costs!

Network compatibility
Depending on your original country, your smartphone may not be 100% compatible with Italian network standards.  In this case, you must purchase and configure the necessary hardware (the hotspot) to have connection, and once you return to your home country, it will no longer be usable.

Tethering blockage
Almost all roaming options do not allow the use of tethering, so the connection is only usable on the smartphone where the sim is located.