To receive notifications via SMS for waitlist announcements (e.g. if a space opens up for you) you will need to add your phone number on your notifications page. Head to My Account>>Account Settings>>Notifications
Select the check box to receive SMS messages for Waitlist announcements. Then enter your phone number and request a verification code.
You’ll then be prompted to add your verification. Once you’ve done that you’ll start receiving SMS notifications for waitlist announcements.