What are the prerequisites for using BankID on mobile?

It is a prerequisite that you have a mobile operator and a bank that supports BankID on mobile. Most operators and banks offer BankID on mobile.

The phone does not have to be a smartphone. The service was created before the smartphone's time and could work on older phones. 

Order a new SIM card if necessary. Enable the service in the online banking, which will then give you a flexible option that does not require a bank code chip.

Customers who have Twin SIM cards must be aware that the service can only be ordered on the primary card. Also, remember that you can only have one BankID on mobile per SIM card.