Its quite The same.
You it doesnt send a sms.
You have to enter a Code which is generated by an App on your Smartphone.
Yes.
Its an app like this: Play Store
The App an be used for more website which are using the two factor authetication (like Google, Microsoft, Twitter, etc)
There are two options for me to implement the sms code
First option: I subscripe to an sms service like this one. They are very expensive!
Second option: I inculde a interface to use such a sms gateway. But there are to many problems...
1. They are to expensive for small website -> no one will use it
2. I can't include all sms gateways so may users dont like the sms gateway i choosed or they already using another sms gatway.
So there isnt any good sense to incude this option.
Otherwise:
The app is free for all. Means: no costs for me and no costs for my customers.
And almost everyone has a smartphone.
I hope you undersad why i will not include the sms verification.
Its not for the registration.
Its for the login. If someone knows your password he cant login because he needs a one time code from your smartphone.