gistfile1.cs

private void IsAlive()
{
    int counter = 0;
    int threadId = Thread.CurrentThread.ManagedThreadId;

    while (keepCheckingConnection)
    {
        Thread.Sleep(1000);

        if (counter != 60)
        {
            counter++;
            continue;
        }
        counter = 0;

        if (keepCheckingConnection)
        {
            bool success = false;
            lock (portLock)
            {

                SerialComPort.DataReceived -= Port_DataReceived;
                SerialComPort.DataReceived += SerialDataReceived;
                try
                {
                    if (SerialComPort.IsOpen)
                        SerialComPort.Close();
                    
                    SerialComPort.Open();

                    EnterCommandMode();
                    success = ModemIsReady();
                    
                    if (success)
                        success = IsConnectedTo(PhoneNumber);
                    
                    EnterDataMode();
                    
                    if (success)
                        success = GetMeterModemSignalStrength();
                }
                catch (Exception exception)
                {
                    success = false;
                    HandleException(exception);
                }

                Thread.Sleep(200);

                SerialComPort.DataReceived -= SerialDataReceived;
                SerialComPort.DataReceived += Port_DataReceived;
                SerialComPort.Close();
            }

            Thread.Sleep(1000);

            if (GsmStatus != GsmStatusEventArgs.Status.Error)
            {
                isConnected = success;
                OnGsmStatusChanged(GsmStatus, success ? Resources.GSMStatus_Connected : Resources.GSMStatus_Disconnected, PhoneNumber);
            }
        }
    }
}