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Time of day routing with Functions

A very common use case for Functions is implementing time of day routing in your application. For example, varying your application's response to incoming calls based on what time and day a customer is calling, or which path to take in an IVR being written with Twilio Studio.

Before getting deeper into the example, first create a Service and Function so that you have a place to write and test your Function 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!

Date and time dependent responses

One potential implementation is to simply respond to callers with a different message depending on the day and time that they are calling. Suppose your business is located on the East coast of the US, and has hours 9am-5pm, Monday-Friday. Calls on those days and between those hours should receive a response indicating that the business is open, while calls on the weekend or outside of business hours should receive a closed message.

This can be accomplished purely by leveraging built-in JavaScript methods, courtesy of the Internationalization API's Intl.DateTimeFormat object. By providing the specific timeZone of your business in the accepted tz format, you can derive the current day and time, and perform any necessary logic to determine your response.

To test this code out, paste the code into the Function that you just created earlier, 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.

Remember that methods such as new Date() return the local time of the machine that your deployed code is being executed on, not your local time. Functions are typically executing in the UTC time zone. This is why all examples are using Intl.DateTimeFormat instead of just the Date object directly.

We highly recommend using built-in objects such as Intl.DateTimeFormat to implement your application logic, or the date-fns library if you need more robust date utilities.

Moment.js is end of life and should not be used for handling time zone shifts, formatting, etc.

Loading Code Sample...

        Responding to a call based on date and time of call

        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));

        Time of day routing in a Studio Flow

        This logic can also be applied in the context of a Studio Flow, such as in an IVR. For example, a Function can return an isOpen property as a boolean (or a more advanced data structure if you like), and a subsequent Split Based On... Widget could then perform pattern matching on that value to determine how the Flow should advance. The following code sample would generate a boolean that can be consumed in a Split Based On... Widget by referencing {{widgets.<widget-name>.parsed.isOpen}}.

        Check out this section of the Run Function widget example to better understand consuming parsed values and generally how to execute this sample via the Run Function widget.

        Loading Code Sample...

              Support time of day routing in Twilio Studio

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