GC75 GSM GPRS Modem - windows application development

I am considering using the GC75 PC Card Modem in a Windows application
to send/receive UDP over GPRS.
I was hoping that someone with GC75 interface programming experience
could expand on the API and tools available or that ship with the
device.
It looks as though the GC75 looks just like another network interface
when using the NDIS driver that ships with the device. But I am unsure
how to concurrently send SMS; by sending an AT command to the device?
And can this be done whilst sending/receiving UDP messages over the
NDIS driver?

Thanks in advance,
Mark