# Normalize telephone numbers

Twilio's APIs consistently use the [E.164](/docs/glossary/what-e164) standard for phone numbers. This format is fine within your code, but it presents a couple of user-facing issues:

* E.164 is difficult to understand when presented as plain text, such as in an SMS
* When read aloud by a Twilio [Say verb](/docs/voice/twiml/say) or [Say Widget](/docs/studio/widget-library/sayplay), numbers such as `+15095550100` will be read literally as a large number, instead of digit-by-digit. (ex. "Plus fifteen billion, ninety-five million, five hundred fifty thousand, one hundred")

Fortunately, [Twilio Lookup](/docs/lookup) enables you to convert a given E.164 phone number into the national format used by that country, which Twilio will read aloud as one would normally say it in their region.

To get started, use the following instructions to create a Function to host your code.

## Create and host a Function

Before you run any of the examples on this page, create a Function and paste the example code into it. You can create a Function in the Twilio Console or by using the [Serverless Toolkit](/docs/labs/serverless-toolkit).

## Console

If you prefer a UI-driven approach, complete these steps in the Twilio Console:

1. Log in to the [Twilio Console](https://1console.twilio.com) and navigate to **Develop > Functions & Assets**. If you're using the *legacy* Console, open the [**Functions** tab](https://www.twilio.com/console/functions/overview).
2. Functions are contained within **Services**. Click **[Create Service](https://www.twilio.com/console/functions/overview/services)** to create a new **[Service](/docs/serverless/functions-assets/functions/create-service)**.
3. Click **Add +** and select **Add Function** from the dropdown.
4. The Console creates a new [protected](/docs/serverless/functions-assets/visibility) Function that you can rename. The filename becomes the URL path of the Function.
5. Copy one of the example code snippets from this page and paste the code into your newly created Function. You can switch examples by using the dropdown menu in the code rail.
6. Click **Save**.
7. Click **Deploy All** to build and deploy the Function. After deployment, you can access your Function at `https://<service-name>-<random-characters>-<optional-domain-suffix>.twil.io/<function-path>`\
   For example: `test-function-3548.twil.io/hello-world`.

## Serverless Toolkit

The [Serverless Toolkit](/docs/labs/serverless-toolkit) lets you develop locally, deploy projects, and perform other tasks through the [Twilio CLI](/docs/twilio-cli/quickstart).

1. From the CLI, run `twilio serverless:init <YOUR-SERVICE-NAME> --empty` to bootstrap your local environment.
2. Go to your new project directory using `cd <YOUR-SERVICE-NAME>`.
3. In the `/functions` directory, create a JavaScript file whose name reflects the purpose of the Function. For example, `sms-reply.protected.js` for a [protected](/docs/serverless/functions-assets/visibility) Function intended to handle incoming SMS.
4. Add the code example of your choice to the file and save it. Note that a Function can only export a single handler. You need to create separate files to run or deploy multiple examples at once.

After you save the Function code, you can test it locally (and optionally tunnel requests to it using a tool like [ngrok](https://ngrok.com/)), or deploy it.

### Run your Function in local development

Run `twilio serverless:start` from your CLI to start the project locally. The Function(s) in your project are accessible from `http://localhost:3000/sms-reply`

* If you want to test a Function as a [Twilio webhook](/docs/usage/webhooks/getting-started-twilio-webhooks), run: `twilio phone-numbers:update <your Twilio phone number> --sms-url "http://localhost:3000/sms-reply"`\
  This automatically generates an ngrok tunnel from Twilio to your locally running Function, so you can start sending texts to it. You can apply the same process but with the `voice-url` flag instead to test with [Twilio Voice](/docs/voice).
* If your code does *not* connect to Twilio Voice or Messages as a webhook, start your dev server and start an ngrok tunnel in the same command with the `ngrok` flag. For example: `twilio serverless:start --ngrok=""`

### Deploy your Function

To deploy your Function and have access to live url(s), run `twilio serverless:deploy` from your CLI. This deploys your Function(s) to Twilio under a development Environment by default, where they can be accessed from:

`https://<service-name>-<random-characters>-dev.twil.io/<function-path>`

For example: `https://incoming-sms-examples-3421-dev.twil.io/sms-reply`

You can now invoke your Function with HTTP requests, configure it as the [webhook](/docs/usage/webhooks/getting-started-twilio-webhooks) for a Twilio phone number, call it from a Twilio Studio [**Run Function** Widget](/docs/studio/widget-library/run-function), and more.

## Respond to a call directly with TwiML

The following Function is one which will tell the user their phone number, in the format that they would expect in normal conversation. This will also work for [international phone numbers](/docs/lookup/v1-api/validation-and-formatting#format-an-international-phone-number)!

To verify this for yourself, paste the code into the Function that you just made, and set it as the **A Call Comes In** webhook handler for the Twilio phone number you wish to test. The following instructions will show you how to do so.

```js title="Convert a number to its national format"
exports.handler = async (context, event, callback) => {
  // The pre-initialized Twilio client is available from the `context` object
  const client = context.getTwilioClient();
  // Create a new voice response object
  const twiml = new Twilio.twiml.VoiceResponse();

  // The From value is provided by Twilio to this webhook Function, and contains the caller's
  // phone number in E.164 format, ex. '+15095550100'
  const from = event.From;

  // Call Twilio Lookup to get information about the number, including its national format
  const result = await client.lookups.phoneNumbers(from).fetch();

  // Read back the caller's phone number in the way it would normally spoken, not as a
  // massive integer!
  twiml.say(`Your phone number is ${result.nationalFormat}`);
  return callback(null, twiml);
};
```

## Set a Function as a webhook

For your Function to react to incoming SMS or voice calls, it must be set as a [webhook](/docs/usage/webhooks) for your Twilio number. There are a variety of methods to set a Function as a webhook:

![Setting a Function as a Messaging webhook using the webhook dropdown option.](https://docs-resources.prod.twilio.com/bf4eae4ac40fe7d47003a93bca295d5c232e0b372358e73ceff931fee3ccdc4f.png)

## Read out phone numbers in a Studio Flow

This functionality also lends itself well to Studio Flows, where you may share a phone number as part of your IVR. The Say widget doesn't natively read E.164 formatted numbers in the national format, but clever use of the Run Function widget with the following sample code will enable this.

### Create a Studio Flow

First, create a new Studio Flow. We suggest following the [Create Your Flow](/docs/studio/tutorials/how-to-build-a-chatbot#create-your-flow) directions from a Studio tutorial.

### Connect and configure your widgets

Once you have created a Flow, drag a [Run Function](/docs/studio/widget-library/run-function) and a [Say/Play](/docs/studio/widget-library/sayplay) widget onto the Studio canvas. Connect the `Incoming Call` trigger to the Run Function widget by dragging from the trigger to on top of the widget, and similarly connect the Run Function widget's "Success" condition to the Say/Play widget.

With the widgets connected, the next step is to configure them.

Click on the Run Function widget, which should cause the Widget Library to show the configuration options for the widget. Name the widget as you like, and use the drop-down menus to select the Service and path of the Function that you created previously. To wrap up the configuration, click **Add** under Function Parameters, set the "Key" to `From`, and "Value" to `{{contact.channel.address}}`. This will cause the phone number of the incoming caller to be passed to the Function as a parameter called `From`.

Your configuration and connections should look similar to this:

![Twilio Studio Flow with Run Function widget for phone number formatting.](https://docs-resources.prod.twilio.com/3c00338740b6fbad536d5debace6d59459896817d703f40d9f7b687aa8e823ab.png)

Following a similar process, configure the Say/Play widget with your desired name, and paste the following into the "Text to Say" field:

```bash
Hi! Your phone number is {{widgets.<widget-name>.parsed.normalizedPhoneNumber}}.
```

Replace `<widget-name>` with the name of your Run Function widget. This means the Say/Play widget will access the results of the Run Function widget, retrieve a value named `normalizedPhoneNumber`, and will attempt to read it back to the caller. You can [read here](/docs/serverless/functions-assets/quickstart/run-function-studio-widget#consume-the-output-of-the-run-function-widget) to get more context around the parsed property.

Click **Publish** to publish your Studio Flow.

### Update your Function's code

With the Studio Flow published and expecting new behavior from your Function, it will need some slight modifications.

Edit or replace the body of your Function with the following sample code. Note that it is returning the `normalizedPhoneNumber` that is expected by the Say/Play widget.

With your code changes complete, save and deploy your Function.

```js title="Normalize a phone number for the Say Widget" description="Provides readable phone numbers to Studio Flows"
// !mark(11,12,13,14,15)
exports.handler = async (context, event, callback) => {
  // The pre-initialized Twilio client is available from the `context` object
  const client = context.getTwilioClient();
  // The From value should be provided as a parameter by the Run Function widget, and contains
  // the caller's phone number in E.164 format, ex. '+15095550100'
  const from = event.From;

  // Call Twilio Lookup to get information about the number, including its national format
  const result = await client.lookups.phoneNumbers(from).fetch();

  // Return the caller's phone number in the way it would normally spoken
  // Access this in a Studio Flow with `{{widgets.<widget-name>.parsed.normalizedPhoneNumber}}`
  return callback(null, {
    normalizedPhoneNumber: result.nationalFormat,
  });
};
```

### Connect and test your Flow

To test your Flow, [connect your Twilio phone number to the Studio Flow](/docs/studio/user-guide/get-started#configure-a-twilio-phone-number-to-connect-to-a-studio-flow).

With your Twilio phone number connected to the Studio Flow, you can call your Twilio phone number and have a synthesized voice read out the number you are calling from in a human-friendly manner.