How to switch between SIM cards in Viking App?
If you use more than one SIM card connected to the same account you will be asked which one of these is default every time you start the app.
If you wish to check the balance or top-up different SIM card than default, you can simply switch between the cards.
For the Androidem device, use the list in the top-left corner of the screen and pick "Balance". Then pick the card.
If you use the app oniOS just click the SIM card icon in top-left corner and you'll get a list of all active cards.
On Windows Phone you can do it by simply using SIM card icon on the panel on the bottom