private void FrmMostrar_Load(object sender, EventArgs e)
        {
            if (centralTelefonica.Llamadas.Count == 0)
            {
                richTextBox1.Text = "No hay datos para mostrar...";
            }
            else
            {
                richTextBox1.Text = centralTelefonica.ToString();
            }

            richTextBox1.SelectAll();

            richTextBox1.SelectionAlignment = HorizontalAlignment.Center;

            richTextBox1.DeselectAll();
        }
        static void Main(string[] args)
        {
            Central    c  = new Central("Movistar");
            Local      l1 = new Local("011", 30, "56216544", 2.65f);
            Provincial l2 = new Provincial("351", Provincial.Franja.Cordoba, 21, "52166452");
            Provincial l3 = new Provincial("261", Provincial.Franja.Mendoza, 44, "43921062");
            Provincial l4 = new Provincial(Provincial.Franja.Jujuy, l2);

            c += l1;
            c += l2;
            c += l3;
            c += l4;

            c.OrdenarLlamadas();

            Console.WriteLine(c.ToString());

            Console.ReadKey();
        }