Voicegain: A Seamless Drop-in Replacement for Nuance Grammar-based ASR

This blog post is intended for anyone responsible for upgrading/migrating an MRCP-based Nuance ASR nearing EOL (End of Life). They can explore how Voicegain ASR simplifies and economically extends the life of existing speech-IVR platforms. It serves as a 'drop-in' replacement for grammar-based Nuance ASR.

Nuance ASR reaching End of Life

There are several hundred (if not thousands) telephony-based speech-enabled IVRs that act as the 'front-door' for all customer service phone calls for enterprises of all sizes. These speech-enabled IVRs are built on platforms like Genesys Voice Portal (GVP), Genesys Engage, Avaya Aura Experience Portal(AAEP)/Avaya Voice Portal , Cisco Voice Portal (CVP), Aspect or Voxeo ProphecyVoiceXML platform and several other such VoiceXML based IVR solutions. The systems predominantly use Nuance ASR as the speech recognition engine.

Unlike contemporary large vocabulary neural-network-based ASR/STT engines, the traditional Nuance ASR is a grammar-based ASR. It uses the MRCP protocol to talk to VoiceXML based IVR platforms. Most of these systems were purchased in the last two decades (2000s and 2010s). Customers typically paid a port-based perpetual license fee (the IVR platforms were also licensed similarly). Most enterprises have a software maintenance/AMC contracts for the Nuance ASR and this is usually bundled along with the IVR platform. The Nuance Recognizer versions in the market vary between 9.0 and 11.0. As of June 2022, Nuance had announced end of support for Nuance 10.0. It is our understanding in speaking with customers that the last version of Nuance sold – Nuance 11.0 Recognizer will approach either end-of-life or end-of-Orderability sometime in 2025*.

Nuance upgrade path is challenging 

Also in speaking with customers, we have understood that customers who currently license the MRCP grammar-based Nuance ASR would have to upgrade to Nuance’s Krypton engine, the new deep-learning based ASR in 2025. Nuance Krypton can only be accessed using the modern gRPC based API and not over MRCP, which makes this upgrade expensive and time-consuming. Because of this, Customers would need to upgrade not just their the ASR but also the entire IVR platform. This is because most legacy IVR platforms - especially would do not support gRPC. This might also entail migrating the existing call flow logic –which is likely written in a VoiceXML app studio or written in a build tool and generated as VoiceXML pages – would also need to be ported.

All of the above steps makes the upgrade process very challenging. While there is a strong case to be made for the merits of upgrading to a deep-learning based ASR to support conversational interactions (better automation rates and more natural user-experience), it is critical for customers that this upgrade/migration is done on the customer’s timelines and not under the gun on the vendor’s clock.

Voicegain as a future-proof drop-in replacement for Nuance ASR

Voicegain offers a drop-in replacement for the Nuance grammar-based ASR. We are the only modern deep-learning/AI (neural-network-based)ASR in the market that natively supports both traditional speech grammars (grxml, SRGS) and large-vocabulary conversational interactions. We are also one of the very few ASR vendors that can be accessed both over a traditional telephony-based protocol like MRCP and a modern web-based method like web-sockets (or gRPC). So the same neural-network model supports both the old and the new protocols. This allows you a future-proof method of replacing Nuance ASR with minimal effort while safeguarding this investment for the long term.

Net-net, by just "pointing" the ASR resource on the VoiceXML platform to the IP-address of the Voicegain MRCP ASR in your network, you can replace the entire Nuance ASR with the Voicegain ASR. Customers would not need to even change or modify a single line of code of the speech-IVR application logic.

In other words, a client can retain the existing telephony/IVR setup and just perform a "drop-in replacement" of Nuance MRCP ASR with Voicegain MRCP ASR.

Longer-term the same Voicegain ASR can perform large vocabulary transcription because it is a neural-network based ASR; so when the customer is ready to replace the directed-dialog Speech IVR with a conversational interaction, the Voicegain platform will already support it.

Get Started for free today

To discuss your upgrade situation in more detail, please contact us over email at can answer any questions that you have. You could also get started with a free developer account by following these instructions. There is no credit card required and we offer 1500 hours of usage for free. Here is a link to the instructions; after you sign up, please contact us at support@voicegain.aiand request MRCP access.

Nuance ASR and Nuance Krypton are trademarks of Nuance, Inc which is now part of Microsoft. Please confirm the End of Life announcement and the protocol capability directly with the company. Our information in this blog post is anecdotal and has not been verified with Nuance.

Voicegain: Voice AI Under Your Control

Voicegain: Build Voice AI apps with our Speech-to-Text and LLM-powered NLU APIs. Record & Transcribe meetings, contact center calls, videos, etc. Get LLM-powered Summary, Sentiment and more. Build Conversational Voice Bots that integrate with your On-prem or cloud CCaaS platform. Get started today.

See how Voicegain works — get a demo of Voicegain today.

Sign up for an app today
* No credit card required.


Interested in customizing the ASR or deploying Voicegain on your infrastructure?

Contact Us → 
Voicegain - Speech-to-Text
Under Your Control