To verify your phone number for two-factor authentication via SMS simply

1. Login to https://login.nashmarkets.com/
2. Tap on Settings
3. Enter your phone number including the country code
4. Tap on Verify 

You will now get a text message to that phone number with a 6-digit code.

To complete the process, please enter the code and tap Verify or if you did not get the code you can resend the code every 20 seconds.

If still not successfully please switch off your device and switch it back on again.