Using SMS as a two factor auth mechanism is on the road-map, but not in the near future. The idea is basically that the server creates a unique code, sends it in SMS, and the user would then copy it back to the login screen. Issue with it is that we first need to allow users to select what two factor auth mechanism they want to use. They could have a hardware OTP token for example, but as they don't have it with them they could use the SMS code as a backup. We also have tons of other things ahead of it in the queue.
I'm a bit curious about your use-case. You basically want a user to login with mobile number + password, and also use a code sent over SMS as a two factor auth? Or do you have something different in mind?