How to connect two computers with a mobile phone

Hi,
In my work I usually have to connect my PC to a computer onboard on a train
through the phone line and update the train computer.



Now I wish to do the same thing by means of a mobile phone in stead of the
phone line. But I don't know how to do this. I have tried to create a
dial-up-networking connection in Win XP SP 2 and forcing the connected
mobile phone to dial up . without success. Windows says that it is possible
if you have a Bluetooth connection between the PC and the mobile phone and I
have it but I can't manage this anyhow. Besides, it prefer to do this by
connecting the PC and the mobile phone with data cable (USB, .). How can I
do this, please help.



Best regards
M Shafaat