Before today, when sharing memories with a contact you needed to provide that contact's email. Backstory would then email that contact letting them know about your shared memories.
Today's release now allows you to use a contact's mobile number instead of an email. When you share an album with a contact's mobile number, Backstory texts the notification about your shared memories.
See which phone numbers we use when sending text messages to your contacts. Please note that you can't send questions or suggestions to the Backstory team using these numbers. They are only for Backstory to send outbound messages.