Modification to C+ app to retrieve SMS from GSM modem (AT commands)

I have an existing windows app (c++) that reads SMS messages from a GSM modem. All it does is read SMS messages - does not need to work with the broadband function of the modem. Currently works with USB GSM modems such as a Huawei E1552. I have a development computer with remote access (team viewer) so if you don't have access to such a modem you can remote login to this PC. Would be helpful if you had some experience with GSM modems and SMS messages. I would like the following improvements 1. Add functionality to read multi-length SMS messages (the main piece of work). Multi-length SMS are when a long SMS by the sender is split into multi-parts and sent as several SMS messages. It contains extra information so that it can be joined together by the phone at the other end. Currently the software cannot read these. For example a 2 part multi-sms message will just show up as 2 blank messages (well just a square in the text area). Currently SMS are being read from the modem via AT commands. I remember the developer saying that to get multi-length SMS, a different mode needed to be used (hopefully someone with GSM experience with SMS will understand what this means :-) 2. Improve 'modem search' functionality. Sometimes it is automatically selecting a com port with no modem on. 3. Improve 'modem connect' status (if possible). Currently it can tell if the modem is removed 4. Fix a issue with error saying 'no settings file' on Vista and Windows 7. Of all these requirements 1 is the most important. If you look into the others and find there cannot be improvements, then it does not matter so much. The code should be your own as I would like to distribute this app without any limitations. Please feel free to ask questions.