It is a wrapper over the firebase functions and code to perform the phone OTP authentication. It simplifies the process and avoids the need to read the Firebase Documentation. It provides three main functions to perform the phone authentication -

1. initPhoneAuth - Initialize firebase and other firebase libraries
2. sendOtp - To send the OTP to the provided phone number
3. verifyOtp - To verify/match the OTP sent

Point to Note: Standard limits as per your firebase plan applies here as well.