Login credentials-USER ID

[MaritaR]

I'm looking to change the login process for my users so that they can use their phone numbers instead of email addresses as their username. What steps should I take to implement this change? Any guidance or resources would be greatly appreciated!

[Mark Manders]

It depends on your setup. Do you have SSO enabled, or are users directly logging into the instance? 

[MaritaR]

I have enabled the external user registration to allow self-registration, but I want my users to input phone numbers instead of email address as username during the log in process and self- registration.