Text to Speech

Overview

Vonage uses text-to-speech engines to allow you to play machine generated speech to your users. This can either be done via an NCCO with the use of the talk action, or by making a PUT request to an in-progress call.

Example

The following NCCO demonstrates an example use case:

[
  {
    "action": "talk",
    "text": "Thank you for calling. Please leave your message after the tone."
  }
]

Locale

You should choose a locale that matches the language type of the text you are asking to be read, trying to read Spanish with an en-us voice for example will not produce good results.

You can set the language code (BCP-47) with a language parameter in the talk command, if you do not specify a language then Vonage will default to an en-US voice. For many languages Vonage offers a choice of voices with different styles. The style parameter maps to features such as vocal range, timbre and tessitura of the selected voice. You can experiment with different styles to find the one appropriate for your use case. You can choose a specific voice style by using the style parameter. By default, the first style (0) is used. Please note not all the voice styles support SSML, see the list of all the supported languages and SSML enabled styles below.

NCCO example with specific voice language and style:

[
  {
    "action": "talk",
    "text": "Obrigado pela sua chamada. Por favor, deixe sua mensagem após o sinal.",
    "language": "pt-PT",
    "style": 6
  }
]

Premium Voices

Some voice styles come with a premium alternative, which through the use of AI, have a more natural sound. To use a premium voice style, add the premium option in your NCCO:

[
  {
    "action": "talk",
    "text": "Obrigado pela sua chamada. Por favor, deixe sua mensagem após o sinal.",
    "language": "pt-PT",
    "style": 6,
    "premium": true
  }
]

Supported Languages

Download the list of voices as a JSON file.

Legacy Voice Names