Telnyx

Syrinx terminates Telnyx Media Streaming and transcodes per the negotiated codec — including wideband G.722, which keeps the top half of the speech band that narrowband μ-law throws away before it reaches your STT.

Start a stream

Start bidirectional media from a Telnyx call to your endpoint with a Call Control streaming_start command (or the equivalent TeXML <Stream> verb):

POST /v2/calls/{call_control_id}/actions/streaming_start
{
  "stream_url": "wss://<your-host>/telnyx?sessionId=<id>",
  "stream_bidirectional_mode": "rtp",
  "stream_bidirectional_codec": "G722"
}

The reference Worker exposes a /telnyx-stream-start helper that builds this payload (or the TeXML) for you.

Codecs

Telnyx negotiates the codec at stream start via stream_bidirectional_codec. Syrinx accepts and transcodes:

Codec	Rate	Notes
`PCMU`	8 kHz	μ-law, the default
`PCMA`	8 kHz	A-law
`G722`	16 kHz	Wideband — kept at 16 kHz to your STT, no downsample
`L16`	16 kHz	Linear PCM

On Cloudflare Workers

The reference Worker binds a TelnyxVoiceConversation Durable Object to /telnyx. The codecs are pure and run on the edge unchanged.

See Codecs, DTMF & transfer for sending DTMF and transferring calls.