3rd Party SMS Notification

Hi there
As you mentioned in PRTG > Setup > Account Settings > Notification Templates > Execute HTTP Action > Payload, "No XML or JSON is allowed. Only the content type application/x-www-form-urlencoded is supported."
So would you please tell me how can i write this code there:

{
  "organization": "xxx",
  "username": "xxx",
  "password": "xxx",
  "method": "send",
  "messages": [
    {
      "sender": "xxx",
      "recipient": "xxx",
      "body": "[%sitename] %sensorid %device %name %status %down (%message)",
      "customerId": 1
    }
  ]
}

And 1 more question:

in PRTG > Setup > System Administration > Notification Delivery > SMS Delivery:
Configuration Mode: Custom URL

How can i implement this URL with my data?

The URL is:

https://MySMSProvider.com/services/URLService/URL/

and the data is:

organization=xxx
username=xxx
password=xxx
command=send
src=123
body=[%sitename] %sensorid %device %name %status %down (%message)

Also you mentioned: "Use the GET method to request the URL. POST requests are not supported."

But i think my request is a POST request.

Thanks a lot

application-x-www-form-urlencoded http-action notification-delivery notification-template sms sms-delivery