Forgot password on telephone

Hi guys,

I picked up user story about 'Forgot password' functionality.

Product owner specified that this functionality should work via SMS (Not via email). 

For example, If I forgot password, I click on the link 'Forgot password?' after I need to enter my phone number.

After that, code (that consist for example 4 digits) was sent to my telephone via SMS, and when I enter that code I could change my password.

Forgot password module couldn't help me at all. 

So do you have some advice how to preform this task? 

Kind regards,

Aleksandar