Is it possible to have a single-operator SIM card?

The procedure for setting up a single-operator profile is as follows:

• Log in to the IoT Portal (click here https://www.thingsmobile.com/login and enter your username and password) 
• Select a SIM card in the “List of SIM cards” section by clicking in the box to the left of it
• Select “Set up the roaming profile” from the options available in the top menu
• Select “My shared data packages”
• Select the roaming profile from those available
• Click the “CONTINUE” button to confirm
Select the “Roaming Profiles” section from the menu on the left to see the coverage for each profile.