Smart IVR · Speech Recognition Reloaded

Smart IVR · Speech Recognition

More and better protocols to improve performance of your interactive phone services.


Speech recognition is a key complementary feature for any IVR in order enables the recognition and translation of spoken language into text for your voice application coding. It is also known as automatic speech recognition (ASR) or speech to text (STT). Smart IVR support today three connectors since the last release 2.x and it has the ability to use them in perfect combination for all services.

◾️ ASR-MRCP Connector

Connector for Nuance Recognizer 9 or upper

This connector is for a legacy speech engine running MRCP v2, today we keep support for the leading speech engine Nuance Recognizer. It requires to connect an MRCP server in order to process speech recognition requests. This method is powered by standard VoiceXML 2.x.

Usage Recommendation:

  • Short words like yes/no
  • Static & Dynamic GRXML grammars
  • Speech Keywords

◾️ ASR-HTTP Connector

Connector for Cloud Speech API with Google, Bing, Alexa

This is the first connector for Cloud Speech API engines like Google, Bing (Microsoft Azure), Alexa (Amazon). This interface use a special VXML integration based on a REST-API request with a subdialog. It’s very easy and reliant for most IVR services.

Usage Recommendation:

  • Natural Language NLP/NLU
  • Dynamic STT
  • Call Steering
  • Voicebots

◾️ ASR-GRPC Connector

Connector for Real-Time Streaming with Google Speech API. *New 2020

This connector is the most advanced method to connect an IVR to latest Speech Cloud API from Google using real-time audio streaming with gRPC. Compare to the previous ones, this connector is a full duplex real-time Speech API integration mode with NLU tag.

Usage Recommendation:

  • Natural Language NLP/NLU
  • Dynamic STT
  • Call Steering
  • Voicebots
  • Conversational AI

Comparision of ASR Connectors

In order to summary available features and key differentiators between each connector, please find bellow a comparition table with most information.

Connectors  ASR-MRCP ASR-HTTP ASR-GRPC
 Speech Engine Nuance 9 or upper Google, Bing, Alexa Google
 Protocol  MRCP v2  REST-API  gRPC
 Grammar  GRXML  Not required  Not required
 Barge-in  Yes  No  Yes
 Connectivity  MRCP Server  Internet  Internet
 Framework  VoiceXML 2.x  VoiceXML 2.0  VoiceXML 2.x extended
 Usage  Tier 2, 3, 4  NLP / NLU  NLP / NLU
 Coding Complex  Easy  Simple (NLU Tag)
 Engine Model  per channel  per transaction  per transaction
 Speed  High  Medium  High (RT Streaming)
 Languages  <100  >120  120
 Version  1.x, 2.x  1.x, 2.x  2.x

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