Web API receive files from GPRS IOT Devices(SIMCONN 800)

How can I directly upload files to url ex .info and .dat files? file path is not available because I am sending from GPRS module so I made this code:

[Route("api/b")]
//[BasicAuthentication]
[HttpPost]
public async Task<IHttpActionResult> PostFiles()
{        
    var result = await Request.Content.ReadAsStringAsync();
    try
    {
        //WriteMsg(result, fileName);
        return Ok();
    }
    catch (Exception e)
    {
        //LogError(e);
        return ResponseMessage(Request.CreateErrorResponse(HttpStatusCode.InternalServerError, e.Message));
    }
}

private void WriteMsg(string result)
    {
        string message = string.Format("Time: {0}", DateTime.Now.ToString("dd/MM/yyyy hh:mm:ss tt"));
        message += Environment.NewLine;
        message += "-----------------------------------------------------------";
        message += result;
        //var statusInfoName = result.Contains(x => x.)
        string path = HttpContext.Current.Server.MapPath("~/UploadedFiles/string.txt");
        using (StreamWriter writer = new StreamWriter(path, false))
        {
            writer.WriteLine(result);
            writer.Close();
        }
    }

it returns this one:

Time: 31/01/2018 01:07:28 PM
    ---------------------------------------------------------------testBoundary
    Content-Disposition: form-data;
    name="fileToUpload"; filename="status.info"
    Content-Type: text/plain

    Node Identifier: 020F7E0A0624
    Node Info: 
    BAT:6880|TEMP:1825|RSSI:-79|IMEI:862631032026154|ICCID:89966098132100451574
    Batteries: 7151mV
    Power Supply Failures: 0
    Power Supply Status: 0
    System Time: 1517429233
    External Resets: 48

    Power Fail Resets: 1


    ----testBoundary

    Time: 31/01/2018 01:07:34 PM
    -------testBoundary
    Content-Disposition: form-data;
    name="fileToUpload"; filename="WmbusData.dat"
    Content-Type: text/plain

    JFpSAQgfRK5McZAkEGgHekowEAX3E3Vw1flfodnLaHnPyf+bUg==

    ----testBoundary

I want to separate file status.info and WmbusData.dat because when I am using ReadAsStringAsync().