Live streaming

wss://api.munsit.com/api/v1/listen?api_key=YOUR_MUNSIT_API_KEY&encoding=linear16&sample_rate=16000

At least one auth method is required. If several are supplied, the api_key query parameter wins.

Connections are rejected with close code 1008 when authentication fails, when the key's concurrent-session limit is reached, or when the wallet balance is below about 60 seconds of runway — the Error message before the close says which.

All optional. Telephony sources typically use encoding=mulaw&sample_rate=8000; microphone capture typically uses encoding=linear16&sample_rate=16000.

Send raw audio as binary WebSocket frames in the encoding and sample rate you declared at connect time. No container headers — for linear16, frames are little-endian 16-bit PCM samples, interleaved when channels=2. Frame size is up to you; roughly 20–200 ms of audio per frame works well.

Controls are JSON text frames, sent on the same socket as your binary audio.

CloseStream and short utterances. CloseStream finalizes the turn in progress. Every event for that turn — Results with is_final: true, then UtteranceEnd, Gender and Sentiment — is sent before the closing Metadata, which is always the last event before the 1000 close.

This holds for utterances shorter than your endpointing window: a 400 ms word closed out with CloseStream still produces a final Results. It does not hold for audio that never opened a turn — under roughly 200 ms of speech, or noise-only input, the voice-activity detector never confirms speech, so the session ends with Metadata (turn_count: 0) and no Results at all. Treat that as “no speech detected” rather than an error.

After sending CloseStream, keep reading until the server closes the socket. Closing it yourself first aborts finalization and loses both the final Results and the billing Metadata.

This is the /listen counterpart to the legacy end_of_stream → finalized flush; the stable-text flag is is_final rather than isFinal, and min_buffer_seconds has no equivalent here.

Every server message is a JSON text frame with a type field. All events carry session_id — and correlation_id when you set one — so multiplexed clients can attribute events without tracking connections.

A single spoken turn produces this sequence:

SpeechStarted → Results (interim, refreshing) → Results (final) → UtteranceEnd → Gender → Sentiment

Endpointing is the silence the engine waits for before declaring a turn finished, and it's the main latency/accuracy dial you control. You can retune it live, mid-session, with a Configure message — drop to 300 when your agent asks a yes/no question, restore 800 for open-ended answers.

Smart turn detection (smart_turn, on by default) runs a semantic end-of-turn model on every pause, so a caller who stops mid-sentence to think isn't cut off just because the silence threshold elapsed. A turn still always ends after 2× the endpointing silence. If the model is unavailable server-side, endpointing degrades gracefully to silence-only.

Interim results (is_final: false) refresh continuously and may revise earlier words — render them as provisional text. UtteranceEnd fires only on genuine turn ends and is the cleanest single signal for “caller stopped talking”.

Pass rare terms — customer names, brands, product codes — in the hotwords query parameter, comma-separated and URL-encoded. Multi-word phrases are allowed.

&hotwords=%D8%B9%D8%A8%D8%AF%20%D8%A7%D9%84%D9%82%D8%A7%D8%AF%D8%B1%2C%D8%A3%D8%AF%D9%8A%D8%A8

Short lists of 5–30 genuinely rare terms work best; very long lists dilute the effect. Up to 200 entries, each up to 40 characters. Entries that can't be applied are skipped and reported in dropped_hotwords on the opening Metadata event — check it to confirm every entry landed.

After each final result you receive two enrichment events, with no extra requests.

On a two-channel call this gives you live per-party gender and a running sentiment trajectory — useful for routing, analytics and supervisor alerts. For post-call analysis of an existing transcription, use Sentiment analysis instead.

Four habits keep a session healthy: send KeepAlive during pauses, pace file streaming to real time, end with CloseStream so the billing event arrives, and handle the close code.

Usage is metered as seconds of audio received × number of channels, charged from your wallet in 60-second cycles during the session.

The closing Metadata event reports the session total as audio_seconds_billed.

Streaming a file, and capturing a microphone in the browser.

Batch alternatives, and the agent frameworks that wrap this socket for you.