Text-to-Speech (TTS)

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• Get Started with Text To Speech
• Text to Speech voices overview
• Available voices and languages
• Text to Speech settings
• Override default settings
• SSML
• Limits
• Pricing

You can provide text and Twilio will synthesize speech in real time and speak back the audio in any call or conference. TTS is available via the <Say> TwiML verb and Studio's Say/Play Widget.

The <Say> verb allows you to provide plain text that Twilio converts to synthesized speech.

For example, when Twilio executes the following TwiML during a call, the caller hears "Hello world!" The synthesized voice the caller hears is the default voice and language of the Twilio Account (configured in the Twilio Console).

<Say> also allows you to modify the language, accent, and voice of the synthesized speech via the language and voice attributes. The example below uses Amazon Polly's "Joanna" voice and American English:

<Say> offers different options for voices, each with its own supported set of languages and genders, so you can customize your application with Text To Speech capabilities according to your needs and preferences.

To start using TTS, complete the following steps:

1. Configure your Account-wide Text To Speech Settings in the Twilio Console.
2. Use <Say> to programmatically define TTS instructions.

Twilio Studio is a visual, serverless tool that uses Widgets to represent various parts of Twilio's platform features and functionality to design and build applications with little or no code.

The Say/Play Widget allows you to add Text To Speech capabilities to your application with ease, including embedding SSML for supported voices.

To start using TTS with Studio, complete the following steps:

1. Configure your Account-wide Text To Speech Settings in the Twilio Console.
2. Use the Say/Play Widget to add TTS to your Studio Flow.

Twilio's Text To Speech offering has a variety of different voices in multiple languages and locales with their associated accents and pronunciations. There are three types of voices with different quality, language coverage and pricing: Basic, Standard and Premium.

Basic voices are first-generation voices. They can be used to get started and familiarize yourself with Text To Speech capabilities using <Say>, but may not have enough human-like qualities to build conversational applications and deliver superior user experiences over a voice call. The voices in this tier are available in a limited number of languages at no cost.

Standard voices offer standard TTS technology and produce natural-sounding synthesized speech with a variety of lifelike voices. The voices in this tier are provided by Amazon (Amazon Polly) and Google (Standard), with support for SSML (Speech Synthesis Markup Language), which allows developers to control many aspects of the synthesized speech.

These voices are generated using the latest technology and innovation in synthesized speech, providing the most human-like, expressive and natural-sounding text-to-speech voices possible, with higher quality than Standard voices. The voices in this tier are provided by Amazon (Amazon Polly Neural) and Google (WaveNet, Neural2), with support for SSML, which allows developers to control many aspects of the synthesized speech.

See the Pricing section below for additional information.

The following table contains all voices available for each language and locale. You can test the different voices from the TTS Settings page in the Twilio Console.

Note: Invalid combination of voice and language attributes may result in error and <Say> instruction failure.

Voices listed with (*) are fully bilingual voices. At the moment only Amazon Polly has this capability for a limited number of voices. Learn more by visiting Amazon's Bilingual Voices documentation.

The Text To Speech page in the Twilio Console allows you to define a default voice and language for your Account. These defaults are used when no language or voice attribute is provided in your <Say> TwiML. If you are using Studio, the defaults are used when "Default" is selected.

You can test different voices and messages in this section of the Console.

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