Nokia 6200 network problem

[TheH]

Hi

I have this nokia 6200..
It's AT&T phone which is tri-band phone.
is it somehow possible to change those network settings on it?
we have here in finland EGSM network which does not work with the phone because it uses GSM850..
It would probably work if i changed my service provider but i don't want to do that.
The phone uses 824-849Mhz for Tx and 869-894Mhz for Rx but it should be 890-915Mhz and 935-960Mhz

And is it possible to flash this phone to 7210 or 6610?

and is it possible to insert finnish T-9 to this phone?

Thanks
TheH