How to verify multiple phone numbers using Firebase OTP Verification without signing in?

I am currently making an Android App where I have to verify each and every person's Phone Number using OTP who is entering the premises. The user operating this is already signed in the app and now needs to verify the phone number of each person entering the premises. How do I do this without signing each time I receive OTP?

I have tried using the regular Firebase OTP Verification but that signs my user in. I don't want that to happen.

This is my mCallbacks Function

mCallbacks = new PhoneAuthProvider.OnVerificationStateChangedCallbacks() {
                @Override
                public void onVerificationCompleted(PhoneAuthCredential credential) {
                    Toast.makeText(getApplicationContext(), "Verification Complete", Toast.LENGTH_SHORT).show();

                    showMessage("Success!!","OTP verified!" + credential);
                    cred = credential;
                    //btn_add_guest.setEnabled(true);

                }

                @Override
                public void onVerificationFailed(FirebaseException e) {
                    Toast.makeText(getApplicationContext(), "Verification Failed", Toast.LENGTH_SHORT).show();
                    Log.i(TAG,"Error is "+e.getMessage());
                }

                @Override
                public void onCodeSent(String verificationId,
                                       PhoneAuthProvider.ForceResendingToken token) {
                    Toast.makeText(getApplicationContext(), "Code Sent", Toast.LENGTH_SHORT).show();
                    mVerificationId = verificationId;
                    mResendToken = token;

                    Log.i(TAG,"VERFICATION ID IS"+mVerificationId);
                    Log.i(TAG,"RESEND TOKEN"+mResendToken);

                }
            };