La llamada durará 30 minutos, no más.

"Results": [
    {
        "Text": "30 minutos",
        "Start": 18,
        "End": 28,
        "TypeName": "datetimeV2.duration",
        "Resolution": {
            "values": [
                {
                    "timex": "PT30M",
                    "type": "duration",
                    "value": "1800"
                }
            ]
        }
    }
]