NetInfoWindow.cs

            if (dictionary.TryGetValue(GlobalNames.External_subscriber_number, out num1))
            {
                // num1.toString added
                 str2 += " External_subscriber_number: Exists but not implemented yet " + num1.ToString();
                // these lines added
                 str2 += Environment.NewLine + GlobalFunction.extnum;
                 GlobalFunction.extnum = "";
            }

SdsParser.cs

    public unsafe bool ParseDigits(
      LogicChannel channelData,
      ref int offset,
      Dictionary<GlobalNames, int> result)
    {
      int num = 0;
      if (result.TryGetValue(GlobalNames.Forward_address_type, out num) && num == 3)
      {
        if (!result.TryGetValue(GlobalNames.Number_subscriber_number_digits, out num))
          return true;
        string empty = string.Empty;
        for (int index = 0; index < num; ++index)
        {
          empty += TetraUtils.BitsToInt32(channelData.Ptr, offset, 4).ToString();
          // this line added
          GlobalFunction.extnum += TetraUtils.BitsToString(channelData.Ptr, offset, 4);
          //
          offset += 4;
        }
...

GlobalFunction.cs

  internal static class GlobalFunction
  {
   ...
     public static string extnum;
   ...