[TortoiseWrath]

I have a T-Mobile 7230 with an AT&T GoPhone SIM, trying to get it to do something more useful than play BrickBreaker. I entered an unlock code generated via this guide, and it said that it accepted it; the SIM Card menu now shows (after entering MEPD):

ID: [SIM card ID, as printed on card]
Personalization:
SIM Disabled
Network Inactive
Network Subset Disabled
Service Provider Disabled
Corporate Disabled
Phone Number: [the phone number associated with the SIM]

All of this information appears correct to me; however, I can't pick up even a GSM signal. When I turn the radio on, it shows "Searching for Network..." for about a minute, then switches to "Out of coverage, no service". An X is shown next to the antenna symbol throughout.

In the "Device information" area (from Alt+Caps+H), it shows 900/1800/1900 GPRS bands, which matches what I've seen online for this device. I am trying to use this in the US, where it is my understanding that 850/1900 is the norm, so it should work on the 1900 MHz band. If it helps, these are also listed:

Network = GPRS
BandType = Extended

All that is shown in Options>Network is "Network: * None *."

Though I think the cause is probably a faulty device, based on what I read here, I think it might be possible that I can receive only the 850 MHz band where I live (a rural area). However, I probably won't have the opportunity to travel to a city anytime soon (the only one available is a Canadian one with a population of about 4500, or some that are 90+ miles away, with the nearest metropolitan area ~150 miles away), so I was wondering if anyone here had any other ideas.

The device had probably never had a SIM card inserted before today; it was used only for Mobipocket development at this location, where we have never gotten T-Mobile service; this is also evidenced by the fact that the only other BB around is a 6220, which wouldn't have any chance of working in North America.