Email & Phone Alias comes into play only when username sign-in option enabled?

Question

##### Scenario #1: user pool sign-in option is set to **Email & Phone number** only.  No **Username**.
I am able to sign-up user & sms verify phone number.   However if i try to login with the phone number, I get UserNotFound Exception.

##### Scenario #2: user pool sign-in option is set to **Email, Phone Number** & **Username** 
I am able to sign-up with dummy username, email & sms verify phone number.  I am able to login with either (phone number, password) or (email, password) combination.

So the Alias (Email or Phone) comes into play only when **username** is set as a sign-in option ?

Answer

You can select only email and phone number without username, but you will have to pick either email or phone number at sign-up as the user identifier. See the Cognito user pool sign-in options information, "If you select only phone number and email, your user will be prompted to select one of the two sign-in options when they sign up". So if you pick email at sign-up, then you can't use phone number to sign in.

Email & Phone Alias comes into play only when username sign-in option enabled?

Scenario #1: user pool sign-in option is set to Email & Phone number only. No Username.

Scenario #2: user pool sign-in option is set to Email, Phone Number & Username

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