How can I check my remaining calling credit?

Text "CONSULT" to 1984.
Go to My Viking. You will be able to see how much calling credit, mobile data, texts and free calling minutes to other Mobile Vikings you have left.
In the My Viking app: thanks to the My Viking app you have a continuous and real-time overview of your remaining calling credit, usage history, contacts and so much more. You can download it here:

iOS: you need iOS 10 or higher.
Android: you need Android 5.0.0 or higher.