Understanding Where TTS Prompts are Played

Which server plays a TTS prompt depends on (a) the configuration of TTS providers and (b) the desired gender/locale/provider for a TTS prompt.

The following is the sequence used to determine which TTS provider plays a TTS prompt:

  1. An Overwritten provider in the TTS prompt.

  2. A System default provider (as configured in the System Parameters through the Cisco Unified CCX Administration web page).

  3. All configured providers, one at a time, in an indeterministic order.

For a detailed description of how the provider selection and fallback works, see Understanding Provider Fallback for TTS.

If any one of these providers can serve the desired locale and gender of the TTS prompt, then that provider plays the prompt. In most cases, the provider is the MRCP TTS server.

There is also a lightweight TTS provider called Cisco LiteSSMLProcessor. This provider can handle only TTS prompts with SSML text that contains only audio elements referring to audio files. In this case, the TTS prompt is played by the Cisco Unified CCX server.

The Cisco LiteSSMLProcessor gets used only under the following two circumstances:

  • The text in the TTS prompt is SSML enabled with only audio elements referring to audio files.

    and

  • None of the providers in the preceding list can serve the TTS prompt request or the overridden/system default provider has been set to Cisco LiteSSMLProcessor.