Soniox STT v6 Adds Agent Text Input and Echo Filtering for Voice Agents

Soniox released STT v6, a speech-to-text model available as stt-rt-v6 for streaming and stt-async-v6 for files across 60+ languages, which accepts the voice agent's own text to better recognize short caller replies and filter out leaked agent audio. Agent text input is enabled via an "enable_agent_text_input" flag on the real-time model only, with text streamed as JSON frames over the same WebSocket as caller audio. Soniox has published no v6 accuracy or latency numbers; v5 scored 1.34% semantic WER on the Pipecat benchmark, and v5 models are deprecated with removal on December 15, 2026.