# Determine carrier, phone number type, and caller info

[Twilio Lookup](/docs/lookup) allows you to get information about phone numbers programmatically. This information can include the name of the phone number's carrier, their type (landline, mobile, VoIP, etc.), the name of the caller, and far more than this example page can cover.

All this data can be indispensable in making your applications dynamic and able to handle different carriers. The following examples illustrate a small sample of what Lookup can enable in Twilio Functions, and we can't wait to see what else you will build.

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

## Create and host a Function

In order to run any of the following examples, you will first need to create a Function into which you can paste the example code. You can create a Function using the Twilio Console or the [Serverless Toolkit](/docs/labs/serverless-toolkit) as explained below:

## Console

If you prefer a UI-driven approach, creating and deploying a Function can be done entirely using the Twilio Console and the following steps:

1. Log in to the Twilio Console and navigate to the [Functions tab](https://www.twilio.com/console/functions/overview). If you need an account, you can sign up for a free Twilio account [here](https://www.twilio.com/try-twilio)!
2. Functions are contained within **Services**. Create a **[Service](/docs/serverless/functions-assets/functions/create-service)** by clicking the **[Create Service](https://www.twilio.com/console/functions/overview/services)** button and providing a name such as *test-function*.
3. Once you've been redirected to the new Service, click the **Add +** button and select **Add Function** from the dropdown.
4. This will create a new [Protected](/docs/serverless/functions-assets/visibility) Function for you with the option to rename it. The name of the file will be path it is accessed from.
5. Copy any one of the example code snippets from this page that you want to experiment with, and paste the code into your newly created Function. You can quickly switch examples by using the dropdown menu of the code rail.
6. Click **Save** to save your Function's contents.
7. Click **Deploy All** to build and deploy the Function. After a short delay, your Function will be accessible from: `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) enables you with local development, project deployment, and other functionality via the [Twilio CLI](/docs/twilio-cli/quickstart). To get up and running with these examples using Serverless Toolkit, follow this process:

1. From the CLI, run `twilio serverless:init <your-service-name> --empty` to bootstrap your local environment.
2. Navigate into your new project directory using `cd <your-service-name>`
3. In the `/functions` directory, create a new JavaScript file that is named respective to 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. Populate the file using the code example of your choice and save. **Note** A Function can only export a single handler. You will want to create separate files if you want to run and/or deploy multiple examples at once.

Once your Function(s) code is written and saved, you can test it either by running it locally (and optionally tunneling requests to it via a tool like [ngrok](https://ngrok.com/)), or by deploying the Function and executing against the deployed url(s).

### Run your Function in local development

Run `twilio serverless:start` from your CLI to start the project locally. The Function(s) in your project will be 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 will automatically generate 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 if you want to test with [Twilio Voice](/docs/voice).
* If your code does *not* connect to Twilio Voice/Messages as a webhook, you can 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 will deploy 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`

Your Function is now ready to be invoked by HTTP requests, set as the [webhook](/docs/usage/webhooks/getting-started-twilio-webhooks) of a Twilio phone number, invoked by a Twilio Studio **[Run Function Widget](/docs/studio/widget-library/run-function)**, and more!

## Identify a phone number's carrier and type

The core functionality of Lookup is determining the carrier and type of a phone number. For example, the following Function code returns true for incoming calls from landline or mobile callers, and false for calls from VoIP callers. An application could use this information to filter out unsupported call types in a Studio Flow if called by a [Run Function widget](/docs/serverless/functions-assets/quickstart/run-function-studio-widget), or simply called as a REST API by your application.

```js title="Lookup with an E.164 Formatted Number"
exports.handler = async (context, event, callback) => {
  // The pre-initialized Twilio client is available from the `context` object
  const client = context.getTwilioClient();

  // Grab the incoming phone number from a call/message webhook via event.From
  // If invoked by a REST API call or Studio Run Function widget, it may be a
  // parameter such as phoneNumber
  // Example: https://x.x.x.x/<path>?phoneNumber=%2b15105550100
  const phoneNumber = event.From || event.phoneNumber || '+15105550100';

  try {
    // Discover the phone number's carrier and type using the Lookup API with
    // the `type: 'carrier'` argument
    const result = await client.lookups
      .phoneNumbers(phoneNumber)
      .fetch({ type: 'carrier' });

    console.log('Carrier name: ', result.carrier.name);
    // 'Carrier name: AT&T'
    console.log('Carrier type: ', result.carrier.type);
    // 'Carrier type: mobile'

    // Reject calls from VoIP numbers, and allow all others
    return callback(null, result.carrier.type !== 'voip');
  } catch (error) {
    console.error(error);
    return callback(error, null);
  }
};
```

## Get a name associated with a phone number

Lookup can also retrieve the name of the individual or business associated with a phone number. Expanding on the previous example, convert the `type` argument to an array, and add `'caller-name'` after `'carrier'`.

If available, the response will include a name for the phone number and whether the name is for a `business` or `consumer`.

> \[!WARNING]
>
> Keep in mind that not all numbers will have names available.

You can then use this information to adjust application logic, format responses to use names to add personalization, and more.

For this example, the code attempts to format the caller's name and use it in a response, falling back to referencing the carrier name if the caller's name isn't accessible. To test this code out, paste the code into your existing Function, 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="Lookup caller name and type"
// !mark(19,25,26,27,28,30,31,32,33,34,35,36)
// lodash is a default dependency for deployed Functions, so it can be imported
// with no changes on your end
const { startCase } = require('lodash');

exports.handler = async (context, event, callback) => {
  // The pre-initialized Twilio client is available from the `context` object
  const client = context.getTwilioClient();

  // Grab the incoming phone number from a call webhook via event.From
  const phoneNumber = event.From;

  try {
    // Create a new voice response object
    const twiml = new Twilio.twiml.VoiceResponse();
    // Discover the phone number's name (if possible) by converting type
    // to an array and appending 'caller-name' to the type argument
    const result = await client.lookups
      .phoneNumbers(phoneNumber)
      .fetch({ type: ['carrier', 'caller-name'] });

    console.log('Carrier name: ', result.carrier.name);
    // 'Carrier name: AT&T'
    console.log('Carrier type: ', result.carrier.type);
    // 'Carrier type: mobile'
    console.log('Caller name: ', result.callerName.caller_name);
    // 'Caller name: DOE,JOHN'
    console.log('Caller type: ', result.callerName.caller_type);
    // Caller type: CONSUMER'

    if (result.callerName.caller_name) {
      // Attempt to nicely format the users name in a response, if it exists
      const [lastName, firstName] = result.callerName.caller_name
        .toLowerCase()
        .split(',');
      const properName = startCase(`${firstName} ${lastName}`);
      twiml.say(`Great to hear from you, ${properName}!`);
    } else {
      // If we don't have a name, fallback to reference the carrier instead
      twiml.say(`We love hearing from ${result.carrier.name} customers!`);
    }

    return callback(null, twiml);
  } catch (error) {
    console.error(error);
    return callback(error, null);
  }
};
```

## Set a Function as a webhook

In order for your Function to react to incoming SMS and/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, as detailed below:

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