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Determine carrier, phone number type, and caller info

Twilio 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 as explained below:

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. If you need an account, you can sign up for a free Twilio account here!
  2. Functions are contained within Services. Create a Service by clicking the Create Service 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 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 accesible from:
    For example:

The Serverless Toolkit enables you with local development, project deployment, and other functionality via the Twilio CLI. 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 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), 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 accesible from http://localhost:3000/sms-reply

  • If you want to test a Function as a Twilio webhook, 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.
  • 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:


For example:

Your Function is now ready to be invoked by HTTP requests, set as the webhook of a Twilio phone number, invoked by a Twilio Studio Run Function Widget, 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, or simply called as a REST API by your application.

Loading Code Sample...

        Lookup with an E.164 Formatted Number

        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.

        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.

        Loading Code Sample...

              Lookup caller name and type

              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 for your Twilio number. There are a variety of methods to set a Function as a webhook, as detailed below:

              You can use the Twilio Console UI as a straigforward way of connecting your Function as a webhook:

              1. Log in to the Twilio Console's Phone Numbers page.
              2. Click on the phone number you'd like to have connected to your Function.
              3. If you want the Function to respond to incoming SMS, find the A Message Comes In option under Messaging. If you want the Function to respond to Voice, find the A Call Comes In option under Voice & Fax.
              4. Select Function from the A Message Comes In or A Call Comes In dropdown.
              5. Select the Service that you are using, then the Environment (this will default to ui unless you have created custom domains), and finally Function Path of your Function from the respective dropdown menus.
                Connect a Function as a Messaging webhook using the Function dropdowns
                • Alternatively, you could select Webhook instead of Function, and directly paste in the full URL of the Function.
                  Setting a Function as a Messaging webhook using the webhook dropdown option
              6. Click the Save button.

              You can also use the Twilio CLI to assign the Function as the webhook of you phone number. You will need a few prerequisites:

              • Twilio CLI installed and executable from your terminal.
              • Either the E.164 formatted value of your Twilio phone number (+1234567890), or its SID (PNXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX).
              • The full URL of your Function (

              Once you have the CLI installed and the necessary information, run the following to connect the Function to respond to incoming SMS:

              twilio phone-numbers:update +1234567890 \

              If you prefer to have the Function respond to incoming calls instead, run:

              twilio phone-numbers:update +1234567890 \

              You may also use the SID of your Twilio phone number instead of the E.164 formatted phone number:

              twilio phone-numbers:update PNXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX \

              You can also use any of the avilable Twilio SDKs to assign the Function as the webhook of you phone number. You will need a few prerequisites:

              • A local development environment for your language of choice and the associated Twilio SDK installed.
              • The SID (PNXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX) of your Twilio phone number.
              • The full URL of your Function (

              In JavaScript for example, you could execute the following code to assign the SMS webhook of your Twilio phone number. The same logic would apply for assigining to a voice webhook, except that the modified property instead would be voiceUrl:

              // Download the helper library from
              // Find your Account SID and Auth Token at
              // and set the environment variables. See
              const accountSid = process.env.TWILIO_ACCOUNT_SID;
              const authToken = process.env.TWILIO_AUTH_TOKEN;
              const client = require('twilio')(accountSid, authToken);
                .update({ smsUrl: '' })
                .then((phoneNumber) => console.log(phoneNumber.smsUrl));
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              Need some help?

              We all do sometimes; code is hard. Get help now from our support team, or lean on the wisdom of the crowd by visiting Twilio's Stack Overflow Collective or browsing the Twilio tag on Stack Overflow.

              Loading Code Sample...

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