gistfile1.txt

{
    "payload": {
        "task": "send",
        "secret": "secret_key",
        "messages": [
            {
                "to": "+000-000-0000",
                "message": "the message goes here",
                "callback": "POST http://server/url?id=123&param=true"
            },
            {
                "to": "+000-000-0000",
                "message": "the message goes here",
                "callback": "POST http://server/url?id=2343&param=true"
            },
            {
                "to": "+000-000-0000",
                "message": "the message goes here",
                "callback": "POST http://server/url?id=9987&param=true"
            }
        ]
    }
}