### Answer Retell uses its own proprietary Automatic Speech Recognition (ASR) engine for speech-to-text conversion. [(1) ]() The ASR engine converts spoken language into written text in real time, forming the first step in enabling AI voice agents to understand and respond to callers. Retell offers two transcription modes: [(2) ]() - Optimize for speed (Fast & Accurate modes) - Optimize for accuracy (Accurate mode) The ASR engine supports 50+ languages and has been optimized for telephonic conversations, which are challenging due to poor connectivity, background noise, and various dialects/accents. You can also use boosted keywords to bias the transcriber model toward domain-specific terms (names, brands, street names, etc.) for improved transcription accuracy. [(3) ]()

​ To learn more, see the sources I considered: [[1] Automatic Speech Recognition (ASR)](https://www.retellai.com/glossary/automatic-speech-recognition-asr) [[2] Smarter Understanding, Clearer Calls: Retell’s ASR Just Got a Major Upgrade | Retell AI](https://www.retellai.com/blog/retell-asr) [[3] Update Voice Agent](https://docs.retellai.com/api-references/update-agent) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

### Answer You're correct—there is community discussion indicating that Retell uses Deepgram Nova 3 for ASR. [(1) ]() The official documentation describes Retell's ASR capabilities and improvements but doesn't explicitly name the underlying provider in the sources I have access to. [(2) ]() [(3) ]() If you're seeing Deepgram or Azure options in your dashboard/settings, that aligns with what community members have noted. The Retell team has stated they "don't own the actual voices" behind certain integrations, which suggests they leverage third-party providers for some ASR/TTS functionality. [(4) ]() For definitive confirmation on which ASR provider is used in your specific configuration, I'd recommend reaching out to the Retell team directly.

​ To learn more, see the sources I considered: [[1] Discord message from @jeffersoncooper_35612 on 2025-06-18](https://discord.com/channels/1186424376300679209/1186462578310910112/1384978999465218079) [[2] Automatic Speech Recognition (ASR)](https://www.retellai.com/glossary/automatic-speech-recognition-asr) [[3] Smarter Understanding, Clearer Calls: Retell’s ASR Just Got a Major Upgrade | Retell AI](https://www.retellai.com/blog/retell-asr) [[4] Retell AI Multilingual ASR Accuracy Issue](https://discord.com/channels/1186424376300679209/1437300079378829434) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.