[Home](./index.md) > [@firebase/auth](./auth.md) > [PhoneAuthProvider](./auth.phoneauthprovider.md) > [verifyPhoneNumber](./auth.phoneauthprovider.verifyphonenumber.md)
## PhoneAuthProvider.verifyPhoneNumber() method
Starts a phone number authentication flow by sending a verification code to the given phone number.
Signature:
```typescript
verifyPhoneNumber(phoneOptions: PhoneInfoOptions | string, applicationVerifier: ApplicationVerifier): Promise;
```
## Parameters
| Parameter | Type | Description |
| --- | --- | --- |
| phoneOptions | [PhoneInfoOptions](./auth.phoneinfooptions.md) \| string | |
| applicationVerifier | [ApplicationVerifier](./auth.applicationverifier.md) | For abuse prevention, this method also requires a [ApplicationVerifier](./auth.applicationverifier.md). This SDK includes a reCAPTCHA-based implementation, [RecaptchaVerifier](./auth.recaptchaverifier.md). |
Returns:
Promise<string>
A Promise for a verification ID that can be passed to [PhoneAuthProvider.credential()](./auth.phoneauthprovider.credential.md) to identify this flow..
## Example 1
```javascript
const provider = new PhoneAuthProvider(auth);
const verificationId = await provider.verifyPhoneNumber(phoneNumber, applicationVerifier);
// Obtain verificationCode from the user.
const authCredential = PhoneAuthProvider.credential(verificationId, verificationCode);
const userCredential = await signInWithCredential(auth, authCredential);
```
## Example 2
An alternative flow is provided using the `signInWithPhoneNumber` method.
```javascript
const confirmationResult = signInWithPhoneNumber(auth, phoneNumber, applicationVerifier);
// Obtain verificationCode from the user.
const userCredential = confirmationResult.confirm(verificationCode);
```