Wireless Sierra AirCard 750

[barristeralfred at aol.com]

 I am from USA and purchased a a wireless Sierra AirCard 750 under a T-Mobile account.  I am now working in Romania and want to decode the card.  It sees the wireless frequency band of 900/100 but I can not get it to work.  It takes a simcard.  How can I decode it so I can use any simcard if it can read the Europe mobile telephone frequency off 900/1800 band?
 
Al in Romania