Purchased an unlocked phone but will it stay that way?

[Midak]

I bought a:
Nokia 3100
V 05.01
15-11-04
RH-50
On the carboard box it came in, one of the tabs said "ver 1.0 09/03"
(I hope that helps)

Anyway, I bought this to use when I go to Irealnd but I wanted to know if I used it in the U.S. with my AT&T SIM, which is now controlled by Cingular, will it lock to AT&T/Cingular? How can I tell if it is locked or not before I go to Ireland?

I checked out that Calculator but I do not know which code to use or what option for the GEN to choose.

Last question Does anyone know any online companies that will sell me an o2 prepaid card and ship it to the U.S. so I know I am set before I go?

[Midak]

Thanks for the heads up on meteor. Last time I was there, my Cingular based Sony Ericson picked up on vodafone, o2 and meteor but that was with the Cingular SIM and the cost per minute was about $2.95 so I'm not doing that again. Funny thing was, that phone worked better in Ireland than it did in New York. So, how do I know if it's locked now since I put the AT&T SIM in there?

[Midak]

I do not have a T-Mobil SIM to put in there, nor do I know anyone who does. If it is unlocked, what will happen if I enter an unlock code?