I think the osclasspoint team will have a solution for this to develop aplugin through which a user can signup by mobile number instead of any email.

Like many other apps.

@abhkhan
There is no good sms gateway that would allow to send sms for free, so it's bit limited idea.

Many clients choose to make several accounts using the same phone number. It should be a way to detect the multiple registration using the same number. Why? This way they can enjoy the registration bonuses.