Entering a WP site with a SMS code

Basically I am trying to figure out a way to do the following;

My customer is trying to have a password protected website. The only catch is he wants visitors to get a specific random password as a reply when said customer sends a SMS to a particular number.

Basically the customer runs a somewhat exclusive clothing line and he wants people to buy or visit the website ONLY if they previously texted the particular cellphone line to get the password.

The process to get to the website would be somewhat like;

The customer knows he has to text a specific number to get a unique password. He texts anything he wants to the number.

The phone line then immediately sends a reply along the lines of: Thank you for your interest in X CLOTHINGS, your unique access code to access our website is UIHR42

The customer then visits a password protected wordpress site and enters this unique one-time password to unlock it.

Is this in any way feasible?