## Update the Customer's phone number

Use this method to update the Customer's phone number. If your integration uses the [Express Checkout Element](/elements/express-checkout-element.md), the phone number is collected directly from the wallet and the value set by `updatePhoneNumber` is not used for express checkout payments.

This method returns a `Promise` that resolves with an object containing the following fields:
* `type`: one of either `"success"` or `"error"`
* `session`: only populated when `type` is `"success"`. Contains a [Session](/js/custom_checkout/session_object) instance representing the updated state.
* `error`: only populated when `type` is `"error"`. Contains an object with a string `message` field which can be displayed to your customer.

- `phoneNumber` (nullable string) **required**
  The Customer's phone number.

### Update the Customer's phone number

```jsx
const checkoutState = useCheckout();
if (checkoutState.type === 'success') {
  const {updatePhoneNumber} = checkoutState.checkout;
  updatePhoneNumber('5554242424');
}
```