Method: CHANNEL
Version: 1.0.0
## Messages

### ConnectRequest

#### Payload Schema

- **command** (string, required)
  Connect message

- **version** (integer, required)
  Protocol version

- **callId** (string, required)
  Call unique identifier

- **applicationKey** (string, required)
  Service unique identifier

- **codec** (string, required)
  Audio codec used for encoding binary audio frames transmitted over the WebSocket connection.
Audio frames are 16-bit signed linear PCM, mono (single channel), with little-endian byte order.

- **sampleRate** (integer, required)
  Audio sample rate in Hertz (Hz). The value is negotiated at call setup via the SVAML `connectStream` command.
Higher sample rates provide better audio quality but increase bandwidth and processing requirements.
- **8000 Hz**: Narrowband telephony quality (standard PSTN)
- **16000 Hz**: Wideband quality, suitable for most voice applications
- **24000 Hz**: High-quality voice
- **44100 Hz**: CD-quality audio
- **48000 Hz**: Professional audio standard
- **96000 Hz**: Ultra high-quality audio

For calls traversing the PSTN, audio is typically sampled at 8 kHz; using a higher value will not improve perceived quality.
  Enum: 8000, 16000, 24000, 44100, 48000, 96000

- **callHeaders** (object, required)
  Arbitrary key/value pairs (header name -> header value).

### ConnectResponse

#### Payload Schema

- **command** (string, required)
  Response to the incoming connection request.
  Enum: answer, busy, reject

### Audio frame (binary)
Raw PCM (Pulse Code Modulation) audio bytes transmitted as a binary WebSocket frame.

**Format:** 16-bit signed linear PCM, mono (single channel), little-endian byte order.

**Frame size:** Audio should be sent in 20ms chunks. At 8 kHz this is 320 bytes per frame (160 samples × 2 bytes);
at 16 kHz it is 640 bytes per frame. Larger chunks are accepted but increase latency.

The sample rate is determined by the value specified in the SVAML `connectStream` command.
Raw PCM audio bytes sent as a WebSocket binary message
### StreamControl
Commands that can be executed on an ongoing stream.

#### Payload Schema

- **command** (string)
  Enum: clear, heartbeat