FNB makes use of both in-app and sms notifications. These are notifications presented to the user via the FNB app installed on the user's device or sent via sms OTP. It's important that the user has an internet data connection to receive the in-app notifications and cellular signal to receive the sms OTPs.
This following forms are required from FNB,
Login - N/A
Payments - In-App Notification
Beneficiary Addition - SMS OTP
The below is an example screenshot of what a typical FNB MFA may appear like.