3Fyll På is an Android application developed by Tre that allows 3Kontant and 3Bredband Kontant customers to easily manage their prepaid accounts. With this app, users can check their balance, view their latest refills, and refill their prepaid cards.

To use the app, users need to register a mobile number as the contact number and add the mobile numbers they want to refill with 3Kontant value vouchers. Users can check the balance of a mobile number by asking the owner of the number to send a SALDO OK message toHowever, they can still refill the number without validating the balance.

In addition, users need to register a debit card to make a refill. If they forget their security code, they can generate a new one by logging out and clicking on the "Forgot security code" button under "Personal settings" on the login page.

3Fyll På can be used even if users do not have money on their prepaid card, and they do not need to be 3 customers to refill a cash number with Tre.