sip/transport library

SIP transports.

Two pluggable implementations:

  • SipWebSocketTransport — ws:// / wss:// to the dart-pbx WS server (Sec-WebSocket-Protocol: sip). Works on every platform Flutter supports, including web.
  • SipUdpTransport — RFC 3261 §18 UDP, one datagram per message. Provided by transport_udp_io.dart on platforms that have dart:io; on web the factory throws UnsupportedError.

Both expose the same surface (SipTransport) so the user agent doesn't care which one it talks over.