Asterisk res_http_websocket does not reliably answer client PING frames
with PONG, so .NET KeepAliveTimeout (default 15s) aborted a healthy idle
ARI WebSocket every ~45s (ping@30s + pong-wait@15s), dropping StasisStart
events so the *100 IVR intermittently answered with no audio. Generous pong
timeout stops the false aborts; genuine drops still caught by the 45s
receive-timeout state re-check and TCP-level WebSocketException.
Surfaced by FlowerCore.Telephony.SipTests Call_Star100_ReceivesAudibleAudioStream
(0 RTP packets while ExtToExt RTP-hook passed).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
d5311de676