You might want to contact AT&T about this- even though you're not connecting to the 3G network (since it's not available in your area) you very well may still need a newer 3G card from them. From what I just read on an AT&T support forum, you should be able to walk into an AT&T store and get a replacement SIM card.
Otherwise, if you know someone with a newer 3G AT&T SIM- try popping that in there. If it still comes up "Emergency Calls Only"... it might have some sort of lock on it. There's no branded
N95-3, so I would assume it's not locked to some other network. It's worth a shot to rule out anything like that though if you can get your hands on someone's SIM card.