Hello @0abzm (0abzm)​ 

Thanks for posting.

In order to achieve this you need to follow two different steps.

The default format for Okta user names is an email address. To give you additional control over the format of Okta user names, you can create a custom character restriction that replaces the email format constraint with a specific set of allowable characters.

Please follow these documents:

https://help.okta.com/en/prod/Content/Topics/users-groups-profiles/usgp-create-character-restriction.htm#:~:text=The%20user%20name%20must%20be,unique%20within%20the%20Okta%20org.

https://help.okta.com/en/prod/Content/Topics/users-groups-profiles/usgp-override-username-format.htm

https://support.okta.com/help/s/article/How-can-I-remove-the-format-restriction-for-Okta-Username-from-using-an-email-address-format?language=en_US

Then, what you are describing about receiving an OTP via SMS is SMS MFA and you can enable it following this:

https://help.okta.com/en/prod/Content/Topics/Security/mfa/sms.htm

Something important to notice is that a password will always be required, and the code sent via SMS is an extra verification, which will also be required.

Let us know if this helps you.

Daniela Chavarria.

Okta Inc.