How to use a Samsung SGH-U700 with GSM 850

Ok I have just bought this phone off ebay. It stated that the phone is compatible with GSM 900/1800/1900. The Samsung website on the other hand stated that the phone is capable of GSM 850/900/1800/1900.

I am wondering where I can get the proper firmware to run the phone on 850 as it seems as that is the band used in my area. Or if there is any other way to get the phone to work on GSM 850.

Thank you all in advance for your help.

I had cingular send it the latest network settings it made it slightly better but not the best.

I know the phone will work on the 850 band because when I get service I can make a phone call once it connects it will start using the 850 network when I hang up it will have 2 or 3 bars and will say limited service and if you try to make a call on it, it will say emergency use only.

Is there a way I can get it to work with AT&T's 850 network in non emergency mode. The SIM chip is a 3G card. Thank you in advance for your help.