Hi everyone.

I need to confirm if the only hardware necesary to use 3G Internet service is the RB411UAHR and the SIM card. Do We need any aditional mini PCI/PCI-e card?

Regards.

There is no 3G module embedded to RB411UAHR.
When SIM card is plugged to RouterBOARD, it is necessary to obtain MiniPCIe card.
AS well it is possible to use USB modem, where SIM card is embedded. (Note that you will need power for USB as the RB411UAHR doesn't have power for USB)