Microsoft Surface Pro Getting Started page 7

Option 1: Use a Nano SIM card
1. Put the enclosed SIM ejector tool in the SIM card tray and push to eject.
2. Put your mobile operator's Nano SIM card in the tray and close it.
3. Go to the Start menu and select Settings > Network & Internet > Cellular.
4. Select SIM 1 in the menu.
Note: For help with your Nano SIM card or cellular service, contact your mobile operator.