How well would these old phones work on today's cingular gsm band?

I'd like to pick up one of these phones for use and novelty and was just wondering since most of them can sue only one band, will they get ANY singnal?

Nokia 8146/8148
From the matrix, I was looking at the Nokia 8146/8148 that uses the GSM 1800 Band.
or
Nokia 9000i Communicator
That only uses the 900mhz band
or
MicroTAC 5200, 7200, 7500, 8200.
They have several some of which can use the 900mhz band the 1800mhz band and one can use both.

Now I also heard that cingular is totally opened it doors to any gsm phone so am I right in thinking if I purchased one of those phones I could use it here in America on the cingular network?

I have links to them but I cant post them