Speech-to-Text WebSocket errors

Error codes and troubleshooting tips for the Telnyx Speech-to-Text WebSocket endpoint, including invalid parameters, engine mismatches, and disconnects.

If you send an invalid parameter (unsupported engine, format, or format/engine combination), the server responds with a JSON error and closes the connection.

Error Response Format

{
  "errors": [{
    "code": "40001",
    "title": "Invalid Parameter",
    "detail": "Unsupported input_format 'aac'. Supported formats: mp3, wav, webm, ogg, flac, ogg_opus, webm_opus, linear16, linear32, mulaw, alaw, opus, amr_nb, amr_wb, g729, speex",
    "source": { "parameter": "input_format" }
  }]
}

Error Codes

Code	Meaning
40001	Invalid input_format value
40002	Format not supported by the chosen engine
40003	sample_rate required but missing (raw encoding or Google with non-WAV/FLAC)
40004	sample_rate is not a valid positive integer
40005	Invalid sample rate for the codec (e.g., amr_nb only supports 8000)
40006	Format not supported by Flux model
40007	Invalid transcription_engine value
40008	Invalid NSS Format: noise_suppression=true with a format other than linear16 or linear32
40009	Unsupported NSS Engine: noise_suppression=true with the Telnyx, Azure, Cohere, or Parakeet engine
40010	Invalid NSS Engine or Invalid NSS Model: unsupported nss_engine or nss_model value
40011	Invalid NSS Quality: nss_quality is not a number from 0 to 1 or a supported preset

See Noise Suppression for the noise suppression parameters.