Simulate callbacks to your own backend with this tool. Below are some samples you can post
Sinch callback documentation
  "event": "ice",
  "callid": "SM2FBXK76NE4DDQ3EJ7SQND4PY@",
  "timestamp": "2015-08-18T02:16:44Z",
  "version": 1,
  "userRate": {
    "currencyId": "USD",
    "amount": 0.0
  "cli": "+15612600684",
  "to": {
    "type": "number",
    "endpoint": "+15612600684"
  "domain": "pstn",
  "applicationKey": "8b9768c5-843c-46e3-b374-79593beb7748",
  "originationType": "pstn",
  "duration": 0
Please keep in mind to have in mind is that Sinch needs to be able to hit your backend with a request so if you want to debug localhost you can use the awesome tool NGROK that we love.

Don't validate the requests when using this tool.