If you have a prepaid SIM card from Comviq and want to switch to a subscription, the easiest way to do it on My Account (Mitt Konto). The change requires BankID. You have two options:
Keep your existing SIM card: Switching to a subscription takes place on the night of the next weekday.
Order a new SIM card: Switching to a subscription takes place after 5 days.
If you have money left on your prepaid card, this balance will be kept and transferred as a balance to the subscription. The balance is then deducted against the next invoice.