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Quick Start Guide

This is a brief walkthrough for setting up and using a Bandwidth voice application. This guide will outline creating a call, receiving a call, and configuring a call.


  • You have already created and set up your Bandwidth Dashboard account.
    • If you have not already done so, please look here for our Account Setup guide.
  • You have created a voice application in the Dashboard UI or using the Dashboard API.
    • Instructions for doing so can be found here.

With an account and application created, we can get started using the Voice API.

Configuring Callback URLs

The voice API can be configured to use multiple different callback URLs to direct traffic and receive input from phone calls. Every application requires a CallInitiatedCallbackUrl, as this is the URL Bandwidth sends an initiated webhook to when an inbound call to a Bandwidth number is made, and a BXML response is expected to continue the call.

For inbound calls, Bandwidth will also send disconnect webhooks to the configured CallStatusCallbackUrl. This webhook is useful for error checking and includes the cause of the disconnect, for example rejected or hung up. You may choose to handle this webhook with the same server you use for standard voice webhooks, or using Pipedream, since it is a great tool for logging these callbacks. If you choose to handle this on a personal server, it is highly recommended to use a unique endpoint to separate these callbacks from other voice webhooks.

For outbound calls, the other most widely used callback URL is the answerUrl in the POST request made to start a call from a Bandwidth number. Like the CallInitiatedCallbackUrl for inbound calls, Bandwidth will expect BXML in the HTTP response this URL to continue the call using BXML verbs.

The CallInitiatedCallbackUrl and answerUrl can be the same or different, depending on if you would like inbound and outbound calls to be handled differently.

Creating a Personal Server

Many of the Bandwidth Samples include code for setting up a local server. When using a locally hosted server, you will not have a valid callback URL, an easy fix for this is hosting your local server somewhere online. A useful tool for hosting local sites on web accessible links is ngrok. Your ngrok link can be used as the domain for your callback URLs.

Using Pipedream

Pipedream is a serverless platform for connecting APIs. Pipedream already has integration for the Bandwidth API. All of the connected tools may be found here. With a Pipedream source or workflow set up, the assigned Pipedream endpoints can be set as your respective callback URLs.

Creating a Phone Call

To create an outbound call from a Bandwidth number, you must make a POST request to our API v2 /calls endpoint. Information about this request can be found on our Voice API documentation page. This can be done using any of our Sample Apps, SDKs, Postman, or in a program you create. Postman is a useful tool for making HTTP requests without needing to write any code. After this call is created, Bandwidth will send a webhook to the answerUrl, expecting BXML in response to continue the call.

Receiving a Phone Call

When a phone call is made to a Bandwidth number, we will send a webhook to the CallInitiatedCallbackUrl, expecting BXML in response to continue the call. An example of this POST request can be found on the Initiate Webhook page.

Your response to this POST request should look like this:

HTTP/1.1 200
Content-Type: application/xml; charset=utf-8

<!-- BXML verbs to process in the call -->

Configuring a Call

After a call is initiated or answered, BXML verbs dictate what will happen on the call. Information on the different types of BXML verbs can be found on the Voice BXML page.

Some BXML verbs will direct a Bandwidth webhook to a URL different from the initiated and answer URLs. These different URLs should be set up on your server to be able to handle different endpoints for different BXML verbs. These endpoints should respond to Bandwdith webhooks with an HTTP response containing BXML telling Bandwidth how to continue the call. It is recommended to set up unique endpoints for unique BXML verbs to avoid clutter and unnecessary complexity. More information about this can be found on the Voice Webhooks page.