Open the WSS media socket (WebSocket)

**This is a WebSocket (WSS) upgrade, not a normal GET.** It carries live call audio between your client and the WUTS Voice engine. Authorize it with a single-use `ct` token from POST /calls/media-token (the bearer is NOT used here). Once open: - **Send** binary frames of raw PCM, signed 16-bit little-endian, mono, 16 kHz (your microphone). ~20 ms / 320-sample frames are ideal. - **Receive** binary frames in the same PCM format (the other party's audio). - **Send** the text frame `{"type":"hangup"}` to end the call. The server pings every 15 s to keep the socket warm across proxies.

curl -X GET "https://example.com/calls/media?ct=string"

{  "success": false,  "error": "validation failed",  "error_code": "VALIDATION_ERROR",  "timestamp": "2026-06-15T12:00:00Z"}