Using Xda2 as wirelsee modem, time out errors

[Butler]

I use a mobile connected to a laptop to send 500k files a lot as I am a travelling photographer. I have used various mobile phones in the past via serial, usb cable or bluetooth and they have worked fine, all be it at 9600 (limited by vodaphone) however with the Xa 2 I connect fine however when I start my ftp the file starts as normal but allways gets time out after about 20% transfer, If I put my SIM into a nokia phone it works fine. Has anyone any idea what I can do about this. I have tried different ftp programs.

[Butler]

I have connected directly to a private modem successfully using Z-modem however I get loads of errors and the file will not send at all, I managed to 5% over once. Is the problem in the moden strings, and if so where do I get the correct driver for the Bluetooth/Xda modem? Or what ar the AT commands>