Programmable Voice API Overview
Twilio's Voice API helps you to make, receive, and monitor calls around the world.
Using this REST API, you can make outgoing calls, modify calls in progress, and query metadata about calls you've created. More advanced call features like programmatic call control, creating conference calls and call queues, call recordings, and conversational IVRs are at your fingertips with Twilio's Programmable Voice.
You can also use the API to route voice calls with global reach to phones, browsers, SIP domains, and mobile applications.
You can obtain numbers by using the Phone Numbers API
All URLs referenced in the documentation have the following base:
The Twilio REST API is served over HTTPS. To ensure data privacy, unencrypted HTTP is not supported.
You can control your connectivity into Twilio’s platform by including your specific edge location in the subdomain. This will allow you to bring Twilio’s public or private network connectivity closer to your applications for improved performance.
For instance customers with infrastructure in Australia can make use of the
sydney edge location by using the base url of:
Voice API Authentication
HTTP requests to the REST API are protected with HTTP Basic authentication. To learn more about how Twilio handles authentication, please refer to our security documentation. In short, you will use your Twilio account SID as the username and your auth token as the password for HTTP Basic authentication.
curl -G https://api.twilio.com/2010-04-01/Accounts \ -u '[YOUR ACCOUNT SID]:[YOUR AUTH TOKEN]'
You can find your account SID and auth token in your console.
To learn more about authentication and interaction with the Twilio REST API, check out our documentation for requests to the API and Twilio's response.
Make and manage calls with the Voice API
Twilio's Voice API lets you make and manage calls programmatically.
To make an outbound call with the API, POST to the Call resource.
You can also leverage the REST API to query metadata and manage state for:
Leverage the helper libraries and Voice SDKs to make or receive calls
Make, receive, or manage calls from any web interface or mobile application.
For step-by-step instructions on how to do this with one of our supported helper libraries or SDKs, check out the quickstarts for:
- iOS – Swift
- iOS – Objective-C
Programmatic call control
The basics of most call flows start with the ability to say strings of text and gather DTMF keypad input.
You can use the Voice API directly to create outbound calls and query and manage state for conferences, queues, and recordings.
Twilio's markup language, TwiML, is the primary language used to control actions on Twilio. For instance, you'll need to use TwiML's <Say> to read some text to a person on a Twilio call.
Twilio provides helper libraries in 6 supported web programming languages: C#/.NET, Java, Node.js, PHP, Python, and Ruby. These helper libraries make including TwiML in your web application a seamless process.
For instance, you can use one of our helper libraries to read some text to a caller and gather their input via keypad: select your language of choice to get started.
Conference calls & Queueing
Twilio's TwiML provides intelligent Conference and Queue primitives to take the heavy lifting out of building seamless call experiences:
- Create a Conference by leveraging TwiML's <Dial> with <Conference>. When you add a caller to a conference this way, Twilio creates a Conference instance resource and a Participant instance resource to represent the caller who joined.
- Use the Conference resource to list the conferences in your account, update a conference's status, and query information about participants in a given conference.
- Learn how to create and manage conference calls from your web applications using Twilio's helper libraries.
- You can create a new Queue by POSTing to the Queue resource or by leveraging the <Enqueue> verb in your TwiML document. Learn how to use Twilio's Queue feature to create a simple call queueing system.
With Twilio's Voice API, you can record, store, and transcribe calls with a little bit of code:
- If you're using the REST API to create your call, set
- You can also generate a recording with TwiML or by doing a POST to the Recording List Resource of a Live Call.
- Learn how to record calls made from your web application, by taking a spin through this tutorial on recording outgoing and inbound calls with the server-side helper libraries.
- Review our support article for options to transcribe your call recording.
Manage SIP calls with Twilio's API
Route calls from your existing VoIP infrastructure to Twilio for programmatic call control – without migrating hardware or carriers with SIP interface.
Programmable Voice SIP lets you route your voice calls with global reach to any landline phone, mobile phone, browser, mobile app, or any other SIP endpoint.
Explore rich communications
Explore the power of Twilio's Voice API with our quickstarts, see how to make calls or respond to incoming calls, modify calls, and more by diving into our collection of tutorials for Programmable Voice.
Build a Conversational IVR
With Programmable Voice and Autopilot, you can build AI-powered conversational IVRs that recognizes user's intent, collects data from users, answers frequently (or infrequently) asked questions, and routes calls to other users.
Autopilot uses natural language understanding (NLU) to detect what users are saying and matches it to Tasks. Tasks can be programmed to collect data, answer questions or connect calls to other users. They are trained to recognize different phrases or ways users might express a given Task.
Explore Autopilot's TwiML noun <Autopilot> or how to build AI-driven voice interactions with Autopilot.
Get help integrating the Voice API
Twilio's Voice API is a flexible building block that can take you from making your first phone call.
While we hope this page gives a good overview of what you can do with the API, we're only scratching the surface: check out our troubleshooting tips to learn about Twilio's debugging tools, common issues, and other tools and add-ons like Voice Insights.
If you need any help integrating the Programmable Voice API or want to talk best practices, please get in touch. You can give us feedback by using the rating widget on this page, talking to support, talking to sales, or reaching out on Twitter.
We can't wait to see what you build!
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.