Hi all, I would like to provide access to users to sign up and I am wondering if this is possible without using the email. 

Many users will have telephone numbers and access to the internet in my country but few will have emails. This is why there are more whatsapp accounts than email accounts. 

Is it possible to make the telephone number the primary contact/username to replace email? How would one go about the authentication and changing system notifications to use the mobile number instead of email? 

Thanks in advance.