using System.IO;
using System.Net.Sockets;
using System.Net;
using System.Runtime.InteropServices;
using System.Diagnostics;


System.Diagnostics.Process Process = new System.Diagnostics.Process();

                Process.StartInfo.UseShellExecute = false;
                Process.StartInfo.CreateNoWindow = true;
                Process.StartInfo.RedirectStandardOutput = true;
                Process.StartInfo.FileName = "rasphone.exe";
                Process.StartInfo.Arguments = "-d 1"; 
                // "-d" ist der Wählparameter, "1"der Name der Verbindung.
                Process.Start();