Speechmatics STT is now available for Voice API

Speechmatics STT is now available in Mission Control, Voice API, and WebSocket transcription. Developers can configure speechmatics/standard for real-time transcription with interim results in live voice workflows.

What's new

• Speechmatics STT engine: Configure Speechmatics as the transcription engine for real-time Voice API transcription.
• Mission Control support: Select Speechmatics from the Mission Control Portal when configuring transcription.
• Standard model support: Use speechmatics/standard for live call transcription.
• Interim results: Receive partial transcripts before final results are returned.
• Telnyx-hosted deployment: Speechmatics runs on Telnyx-hosted infrastructure in Atlanta instead of the public Speechmatics SaaS endpoint.
• 17+ language options: English, Spanish, Arabic and English, Mandarin and English, English and Malay, English and Tamil, Tagalog, Spanish and English bilingual, Mandarin, English, Malay and Tamil, Bashkir, Basque, Galician, Irish, Maltese, Mongolian, Swahili, Uyghur, and Welsh.

Why it matters

• Gives voice AI developers another real-time STT option through Telnyx Voice API.
• Lets teams configure Speechmatics in Mission Control or through API-based workflows.
• Keeps transcription inside Telnyx-hosted infrastructure for the current deployment.
• Reduces integration work by exposing Speechmatics through existing Telnyx transcription configuration.
• Supports multilingual voice workflows that need bilingual and regional language coverage.
• Sets a clear current boundary: Italian is not included until it is added to the Telnyx docs and API schema.

Example use cases

• Voice AI agents that need real-time partial transcripts while a caller is still speaking.
• Contact center workflows that route live call audio through Speechmatics transcription.
• Multilingual support flows using Arabic and English, Mandarin and English, English and Malay, or English and Tamil packs.

Getting started

1. Sign up or log in to the Telnyx Mission Control Portal.
2. Configure transcription in Mission Control and select Speechmatics as the STT engine, or obtain your Telnyx API key for API setup.
3. For Voice API, start transcription on an active call with transcription_engine set to Speechmatics.
4. Set transcription_model to speechmatics/standard.
5. Place a test call and verify transcript callbacks.

curl -X POST "https://api.telnyx.com/v2/calls/{call_control_id}/actions/transcription_start" \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "transcription_engine": "Speechmatics",
    "transcription_engine_config": {
      "transcription_engine": "Speechmatics",
      "language": "en",
      "transcription_model": "speechmatics/standard",
      "interim_results": true
    }
  }'

Learn more in the Speech-to-Text models documentation.