我终于得到它这片code的工作：

I finally got it working with this piece of code:

 string messageToCallInPatient = "The doctor is ready to see you in 5 minutes. Please wait outside room " + roomName;
 string url = "http://x.x.x.x/cgi-bin/npcgi?no=" + phoneNumber + "&msg=" +
               messageToCallInPatient;
 HttpWebRequest webReq = (HttpWebRequest)WebRequest.Create(string.Format(url));
 webReq.Method = "GET";
 HttpWebResponse webResponse = (HttpWebResponse)webReq.GetResponse();

 //I don't use the response for anything right now. But I might log the response answer later on.   
 Stream answer = webResponse.GetResponseStream();
 StreamReader _recivedAnswer = new StreamReader(answer);