CM.com Voice API applications support different types of prompts.
Plain text TTS (Text-to-Speech)
All Voice API applications supports plain text TTS. The text given in each prompt step will be converted to speech. Different voices and languages are available. Premium TTS voices offer a more natural voice. A complete list of voices and languages is available here.
TTS using SSML
Speech Synthesis Markup Language (SSML) allows for more control over TTS prompts. Pauses, speed, volume and pitch can be controlled using SSML. SSML is supported for all voices and languages.
Custom audio files
In order to use custom audio files with Voice API applications, you need to upload a set of audio files in the following directory structure using the Voice Management App in the Audio files section:
/spelling/en-GB/*.wav
Where ‘en-GB’ is the language (including locale) of the set. This language is specified for the Voice API and defaults to ‘en-GB' when omitted. Inside this folder, you need to upload a .wav file for every number or letter possible in the code prompt, like:
0.wav
1.wav
2.wav
a.wav
b.wav
c.wav
When using custom audio files for non-spelling prompts, each prompt is read from the file with the corresponding name from the root of the file structure in the Audio files section of the Voice Management App.