Sandbox is down

I am trying to create a sandbox account, but all attempts to access https://service.devtest.ringcentral.com with Chrome, Firefox or Edge all fail. It just shows a JSON payload with an error message:

{
  "errorCode" : "CMN-201",
  "message" : "Service Temporary Unavailable",
  "errors" : [ {
    "errorCode" : "CMN-201",
    "message" : "Service Temporary Unavailable"
  } ]
}