I am developing Android app using Firebase. Because of that, I want to use Firebase Auth. I have following requirements:

* Register/Log in using Facebook
* Register/Log in using Email/Password
* Register/Log in using **Phone Number/Password**

The first two are OK, I followed basic [tutorials](https://firebase.google.com/docs/auth/). However, **Phone Number / Password** is the problem here. Firebase supports only Phone Number/SMS Token for this (its called Phone Auth), but there is no mention about my case. I do not want to hack Firebase and use its realtime database instead of Auth 'database'. Is there any better way to achieve this? 

Thank you.