I have implemented Firebase authentication in my android application. I want to implement Authentication with OTP verification but when I try to authenticate with OTP it won’t send OTP. Instead of OTP I get an error:

[SmsRetrieverHelper] SMS verification code request failed: unknown status code: 17499 BILLING_NOT_ENABLED

I’m new to android development and I set minSdk and targetSdk. also add SHA 1 key and SHA 256 in my Firebase console.

This is my code of SendOTPActivity.java:

public void onClick(View view) {
                if (inputMobile.getText().toString().trim().isEmpty()) {
                    Toast.makeText(SendOTPActivity.this, "Enter Mobile", Toast.LENGTH_SHORT).show();
                    return;
                }
                progressBar.setVisibility(View.VISIBLE);
                buttonGetOTP.setVisibility(View.INVISIBLE);

                PhoneAuthProvider.getInstance().verifyPhoneNumber(
                        PhoneAuthOptions.newBuilder(FirebaseAuth.getInstance())
                                .setPhoneNumber("+91" + inputMobile.getText().toString()) // Phone number to verify
                                .setTimeout(60L, TimeUnit.SECONDS) // Timeout and unit
                                .setActivity(SendOTPActivity.this) // Activity for callback binding
                                .setCallbacks(new PhoneAuthProvider.OnVerificationStateChangedCallbacks() {

                            @Override
                            public void onVerificationCompleted(@NonNull PhoneAuthCredential phoneAuthCredential) {
                                progressBar.setVisibility(View.GONE);
                                buttonGetOTP.setVisibility(View.VISIBLE);
                            }

                            @Override
                            public void onVerificationFailed(@NonNull FirebaseException e) {
                                progressBar.setVisibility(View.GONE);
                                buttonGetOTP.setVisibility(View.VISIBLE);
                                Toast.makeText(SendOTPActivity.this, e.getMessage(), Toast.LENGTH_SHORT).show();
                            }

                            @Override
                            public void onCodeSent(@NonNull String verificationId, @NonNull PhoneAuthProvider.ForceResendingToken forceResendingToken) {
                                progressBar.setVisibility(View.GONE);
                                buttonGetOTP.setVisibility(View.VISIBLE);

                                Intent intent = new Intent(getApplicationContext(), VerifyOTPActivity.class);
                                intent.putExtra("mobile",inputMobile.getText().toString());
                                intent.putExtra("verificationId",verificationId);
                                startActivity(intent);
                            }
                        }).build()
                );
            }

I expect OTP verification on my real android device without billing account. As I’m new to android development I want to learning Firebase authentication with OTP.