matrix-spec/event-schemas/examples/m.call.candidates

{
  "age": 242352,
  "content": {
    "version" : 0,
    "call_id": "12345",
    "candidates": [
      {
        "sdpMid": "audio",
        "sdpMLineIndex": 0,
        "candidate": "candidate:863018703 1 udp 2122260223 10.9.64.156 43670 typ host generation 0"
      }
    ]
  },
  "origin_server_ts": 1431961217939,
  "event_id": "$WLGTSEFSEF:localhost",
  "type": "m.call.candidates",
  "room_id": "!Cuyf34gef24t:localhost",
  "sender": "@example:localhost"
}