Windows mobile as GSM Modem

[hugot]

Is there any way of making an windows mobile device working as a gsm modem?

[levenum]

Depends on the particular device.
WM 5 and up devices have something called "modem link" or in WM 6 "internet sharing".
Basically it shares phones cellular internet over USB, IR or BT (WM 6 only). When turned on you device identifies it self to the PC as USB modem. You will likely need drivers from the CD that came with the phone though.